Computer System Validation - CSV

Table of Contents

Computer System Validation (CSV) is a documented process pivotal in ensuring that computerized systems operate precisely as they’re intended, achieving consistent, reliable results crucial for regulatory compliance, product quality, and data integrity across vital industries such as pharmaceuticals, biotechnology, and medical devices. 

This regulatory requirement not only substantiates the operational integrity of IT systems but also maintains stringent adherence to GxP regulations, playing a fundamental role in safeguarding data integrity and ensuring the production of reliable outcomes.

What Is a Computerised System?

“System containing one or more computers and associated software, network components, functions controlled by them and associated documentation.”

GAMP® 5 International Society for Pharmaceutical Engineering (ISPE)

A computerized system refers to a setup or arrangement where software and hardware components are integrated and coordinated to perform specific, automated functions within an organization or enterprise. These systems are designed to handle tasks that traditionally require human intervention, thus enhancing efficiency, accuracy, and processing speed across various operations.

Key Components of a Computerized System

Key Components of Computerized Systems - CSV

  • Hardware: This component includes all the physical devices and equipment that are part of the computer system. Hardware encompasses servers, computers, network routers, switches, and peripherals like printers and scanners. These devices provide the essential infrastructure that supports the operation of software applications and the management of data.
  • Software: Software refers to the programs and operating systems that run on the hardware. These applications execute specific tasks, manage data flows, and provide interfaces for user interaction. Software can be categorized into system software, such as operating systems and utility programs, and application software, like database systems and specialized analytical tools.
  • Data: Data is a critical component and represents the information processed, stored, and generated by the computer system. It includes everything from input data entered by users to information stored in databases and outputs generated by software applications. Effective management of data ensures that it is accurate, accessible, and secure, facilitating informed decision-making and operational workflows.
  • Process: The processes involve the methods and protocols governing the use and operation of the computer system. This includes standard operating procedures (SOPs), user guidelines, and protocols for data entry, data processing, system maintenance, and security measures. Processes are designed to maximize the efficiency and reliability of the system, ensuring that all activities are conducted in a controlled and repeatable manner.

What is Computer System Validation?

Computer System Validation (CSV) is defined as a documented process that verifies a computerized system performs exactly as it is designed to do in a consistent and accurate manner. This process is crucial to ensure that systems operate consistently and produce results that meet predetermined specifications. 

CSV is applicable to a wide range of computerized systems used in pharmaceutical, biotech, and other industries. These systems range from infrastructure software and non-configured systems to configured products and custom systems. 

The primary objectives of CSV are to ensure that these systems can produce data accurately and consistently, maintain an indelible electronic data trail that is transparent, traceable, and tamper-proof, and store electronic data records securely.

This involves a series of validations including Installation Qualification (IQ), Operational Qualification (OQ), and Performance Qualification (PQ), which demonstrate the system’s suitability for its intended purpose. These processes ensure the integrity of data processing and uphold the quality of the product, adhering to GxP regulations.

Regulatory Requirements for Computer System Validation

Regulatory requirements for Computer System Validation (CSV) are critical in ensuring that computerized systems involved in the manufacture, testing, and quality assurance of pharmaceuticals and medical devices are compliant and fit for purpose. 

FDA

The U.S. Food and Drug Administration (FDA) maintains stringent requirements for computer systems used in the pharmaceutical, biotechnology, and medical device industries. These systems are considered crucial equipment under 21 CFR 211.68, requiring rigorous validation to ensure they perform their intended functions accurately and reliably. 

21 CFR Part 11 sets the standards for electronic records and electronic signatures, stipulating that they must be as reliable, trustworthy, and tamper-proof as their paper counterparts. This part of the Code of Federal Regulations applies to a wide range of FDA-regulated industries, including pharmaceuticals, medical devices, and biotechnologies, among others. The requirements are designed to ensure that electronic forms of data are suitable for submission to the FDA and can legally replace traditional paper documents and handwritten signatures.

Moreover, the FDA has established specific controls for electronic records and electronic signatures outlined in 21 CFR Part 11, which is vital for maintaining the integrity and security of digital data.

Annex 11

Annex 11 of EudraLex Volume 4 applies to all forms of computerized systems used as part of GMP-regulated activities. This annex aims to ensure that computerized systems are properly designed, validated, operated, and maintained to assure the integrity of data and functionality relevant to product quality. The primary focus of this annex is on managing risks to data integrity and system functionality, which are critical to product quality and patient safety.

ISO 13485

ISO 13485:2016 emphasizes the need for a quality management system that consistently meets both customer requirements and regulatory requirements applicable to medical devices and related services. 

Under this standard, computer systems, whether they are part of the production process or the medical device itself, must be validated to demonstrate their suitability and reliability for specific purposes. This validation is essential because these systems are integral to the quality, efficacy, and safety of the device.

Where is Computer System Validation Used?

Computer System Validation (CSV) is a critical practice required in various industries to ensure that computerized systems perform accurately and consistently as intended, especially in environments governed by regulatory compliance. 

CSV is extensively applied in sectors where systems are used in the research, clinical testing, manufacturing, distribution, and storage processes associated with pharmaceuticals, biotechnology, medical devices, and other FDA-regulated industries.

Process Control Software

This type of software is used to manage and control manufacturing processes, ensuring they operate within specified parameters. It is crucial for maintaining the quality and efficiency of production.

PLC (Programmable Logic Controllers) for Controlled Packaging Equipment
PLCs are used for the automation of machinery in packaging operations, requiring validation to ensure reliable, precise control that conforms to manufacturing standards.
SCADA (Supervisory Control and Data Acquisition)
SCADA systems are vital for the centralized control of manufacturing processes, where data acquisition is critical. Validation ensures these systems can reliably monitor and control the processes they oversee.
DCS (Distributed Control System)
A DCS manages complex, large-scale industrial operations. CSV for DCS ensures that all parts of the control system communicate effectively and operate without failure.

Commercial Off-The-Shelf (COTS) or Software as a Service (SaaS) Software

Even standard commercial software applications and cloud-based services used in regulated environments require validation to confirm they meet specific regulatory requirements for security, data integrity, and performance.

LIMS (Laboratory Information Management Systems)
LIMS are essential in managing laboratory data and operations. Validating these systems ensures that they can reliably manage samples, data, and associated workflows.
Clinical Trial Monitoring Systems
These systems manage and monitor clinical trial data, requiring validation to ensure data accuracy, integrity, and confidentiality are maintained throughout the trial process.
Chromatography Data Systems (CDS)
Used in both research and quality control laboratories, CDS manages the data from chromatography instruments. Validation is necessary to ensure their reliability in analyzing and reporting data.
ERP (Enterprise Resource Planning) Systems:
ERP systems integrate core business processes and require validation to ensure they function correctly, providing accurate real-time data across the organization.
MES (Manufacturing Execution Systems)
MES manages and monitors work-in-process on a factory floor, requiring validation to ensure they can optimize production effectively and reliably
Batch Record Systems
These systems track and document the manufacturing process details, which is crucial for compliance and quality assurance.
BMS (Building Management Systems)
BMS controls and monitors the building's mechanical and electrical equipment like ventilation, lighting, power systems, fire systems, and security systems; validation ensures these controls are functioning correctly.
Cloud-Based Software Services
As more companies store data and operate applications through cloud services, validating these platforms is essential to ensure they meet compliance standards for security and data integrity.
Spreadsheets
Often used for data entry, calculations, and reporting, even spreadsheets need to be validated for accuracy and reliability when used in regulated environments.

CSV is integral to ensuring that these diverse systems remain reliable, secure, and effective in their roles within highly regulated industries. Each application of CSV is tailored to the system’s specific functions and the regulatory requirements it must meet, highlighting the importance of a comprehensive validation process.

Steps Involved in the CSV Process

Steps involved in CSV - Computer System Validation

The GAMP® 5 guidelines, developed by the International Society for Pharmaceutical Engineering (ISPE), provide a structured framework for validating computerized systems in the pharmaceutical and medical device industries. 

These guidelines emphasize a lifecycle approach to Computer System Validation (CSV), which facilitates compliance, efficiency, and reliability throughout the entire duration of the system’s use. Here’s a detailed breakdown of the lifecycle phases as per GAMP® 5 and the supportive activities that intersect these phases:

Concept Phase

The Concept Phase serves as the foundation for implementing a new computerized system in regulated environments like pharmaceuticals and medical devices. This initial stage is critical for setting the stage for a successful validation process, ensuring that the system will meet both business needs and regulatory requirements.

Planning

During the planning activity, the groundwork is laid for the entire project. Here, the team:

  • Defines overall system requirements: This includes understanding what the system is supposed to achieve, its critical functionalities, and the impact it will have on current processes.
  • Assesses hardware and software options: Various technology platforms are evaluated to determine which best fits the project’s needs.
  • Considers regulatory impacts: How the system will need to comply with relevant regulations is critically assessed.
  • Evaluates system complexity and novelty: Newer and more complex systems might require more rigorous testing and validation strategies.
  • Plans for document control and testing: This involves deciding how documents will be managed and what testing will be required to ensure the system operates as intended and is maintainable.
  • Determines data management needs: It is important to plan what data and records will be generated and how they will be retained.

System Software Categorization

Understanding the type of software is crucial as it dictates the validation strategy:

  • Software Category 1 – Infrastructure Software: Such as operating systems, database engines, and network tools, which support applications.
  • Software Category 3 – Non-Configured Software: Includes software that allows basic parameter settings without being configurable, like firmware or basic instrument applications.
  • Software Category 4 – Configured Software: This category includes software that can be tailored to specific business processes without altering the code, such as LIMS, ERP systems, and DCS.
  • Software Category 5 – Custom Software: Fully customized solutions developed to meet unique business process requirements, including custom applications and firmware.

Risk Assessment

This proactive risk assessment focuses on identifying potential failure modes of the computer system and their possible impacts on product quality, patient safety, or data integrity. The aim is to:

  • Predict and prioritize potential risks: Identifying scenarios that could lead to failures and assessing their likelihood and potential impact.
  • Develop mitigation strategies: Creating plans to reduce or eliminate risks, ensuring the system’s reliability and compliance.

RELATED ARTICLE: Risk Assesment in Pharma Industry

Supplier Assessment

Choosing the right vendor is key to the project’s success. This activity involves:

  • Sending Requests for Services (RFS): This document outlines the system requirements for potential vendors.
  • Reviewing vendor responses: Evaluating how well each vendor’s solution meets the specified requirements and their cost implications.
  • Requesting demonstrations: Before making a final decision, seeing a live demonstration can provide additional insights into the system’s capabilities and user interface.
  • Conducting in-depth supplier assessments: Further evaluating the selected vendors to ensure they can reliably meet the project’s needs and comply with industry regulations.

Project Phase

The Project Phase in Computer System Validation (CSV) involves the detailed planning and execution necessary to ensure the system meets specified requirements and is ready for operational use. This phase transitions from conceptualization to tangible outputs, culminating in the handover of the fully validated system to the end-user or client. Below is an in-depth exploration of the specific activities involved in this phase:

Planning

The planning activity within the Project Phase establishes the scope and approach of the validation effort. This includes:

  • Defining validation scope: What aspects of the system will be validated.
  • Determining validation approach: How the validation process will be conducted.
  • Assigning roles and responsibilities: Clearly delineating who is responsible for each part of the validation process.
  • Setting acceptance criteria: Establishing the standards the system must meet to be considered validated.

Documentation includes:

  • Validation Master Plan (VMP): This document is crucial for outlining the strategy for validation across the organization. It may be segmented by site, department, or system, depending on the organization’s size and structure.
  • System Overview: Provides a comprehensive description of the system, including its hardware, software, data, and operational context. This overview helps ensure regulatory compliance and facilitates understanding of the system’s environment and functionality.

Utilizing the CSV Process V model

GAMP5 V Model of Computer System Validation - CSV

The V Model is a structured approach that maps out the stages of system development alongside corresponding validation activities:

  • Left side of the V Model: Specifications are developed for the system.
  • Right side of the V Model: Testing and verification activities confirm that the specifications are met.

Risk Assessment

Risk assessment during the Project Phase involves:

  • Evaluating risks at each stage of the V Model: Ensuring that the identified risks are continuously considered and mitigated throughout the development and validation processes.

Writing Standard Operating Procedures

SOPs are essential documents that dictate how to use the computer system properly:

  • Purpose of SOPs: To ensure that all users understand and consistently follow the procedures required to operate the system within its validated state.

Training

Training is critical to ensure that the system is used correctly and effectively:

  • Training content: Should cover how to use the system and its software, as well as any specific procedures related to the system’s operation.
  • Target audience: Key users, system administrators, and anyone who will interact with the system.

Handover

The handover activity finalizes the project and transitions the system for operational use:

  • Handover plan: Outlines the process for moving the system into the operational phase, managing any disruptions, and ensuring the system is supported appropriately.
  • Verification elements in handover: Confirm that the system is fit for purpose, roles and responsibilities are clearly defined, all relevant personnel is trained, and quality controls are in place to maintain ongoing compliance.

During the handover, it’s also crucial to verify that any residual risks have been formally accepted and that the system is ready for regular operational use. This process involves a thorough review and final adjustments based on user feedback and test results.

Operation Phase

This phase ensures the system operates effectively and remains compliant with regulatory requirements after it goes live. Key processes and activities must be established and maintained to safeguard the integrity, security, and functionality of the system throughout its operational life.

Data

Computerized systems that exchange data electronically must include robust checks for correct and secure data entry and processing. These measures are essential to minimize risks associated with data integrity and security.

SEE ALSO: Data Integrity and Data Governance in GMP

Accuracy Checks

For critical data entered manually, it is imperative to have mechanisms in place for verifying accuracy. This can be accomplished through checks by a second operator or by validated electronic systems, ensuring that errors are minimized.

Data Storage

Data must be protected through both physical and electronic means to prevent damage. It’s crucial to regularly verify that stored data remains accessible, readable, and accurate throughout its retention period.

Regular backups are necessary, and the integrity and accuracy of the backup data must be validated and monitored periodically to ensure it can be restored if needed.

Printouts

Systems should enable the generation of clear printouts of electronically stored data. For GMP-critical records, such as those supporting batch release, printouts should clearly indicate any data alterations post the original entry.

Audit Trails

Systems should incorporate audit trails that record all changes and deletions of GMP-relevant data, including the reasons for such changes. These trails should be regularly reviewed and maintained in a format that is easy to understand.

Change and Configuration Management

Any modifications to the system, including updates to configurations, should be conducted in a controlled manner, following strictly defined procedures to maintain system integrity and compliance.

Periodic Evaluation

Periodic evaluations of the computerized systems are crucial to confirm they remain valid and compliant with GMP. These evaluations should review functionality, deviations, incident histories, and overall system performance and security.

Security

Appropriate physical and logical controls must be implemented to limit system access to authorized personnel only. This includes using passwords, biometrics, and restricted physical access to ensure that unauthorized entry is prevented.

The creation, alteration, and revocation of access should be carefully recorded to ensure accountability.

Incident Management

All incidents, not just system failures or data errors, should be reported and analyzed to identify root causes. This analysis is fundamental for developing effective corrective and preventive actions.

Electronic Signature

Electronic signatures should be treated with the same level of importance as handwritten signatures within the organization and must be irrevocably linked to their respective records, including timestamping.

Batch Release

Computerized systems used for batch certification should allow only qualified personnel to certify batch release. This should be clearly documented and performed using electronic signatures.

Business Continuity

Provisions must be in place to maintain critical processes in the event of system failure, including manual or alternative systems. The appropriateness and readiness of these alternatives should be based on risk assessments and regularly tested.

Archiving

Archived data should remain accessible, readable, and intact. If system changes are anticipated, the ability to retrieve archived data must be tested and assured.

Retirement Phase

The Retirement Phase marks the end of the lifecycle for a computerized system in regulated environments such as pharmaceuticals and medical devices. This phase involves meticulous planning to ensure that data handling meets compliance requirements, including data migration, archiving, and destruction. 

Proper execution during this phase ensures that critical and sensitive data is preserved or disposed of following regulatory standards and that the transition to new technology is smooth and secure.

Data Migration

Data migration is a critical task that involves transferring data from the existing system to a new platform. This process must be carefully planned and executed to ensure that all necessary data is accurately moved while maintaining its integrity and context. The data migration plan should cover:

  • Comprehensive transfer of necessary data: Ensuring that no critical data is left behind.
  • Preservation of data context and metadata: The relational information and metadata that describe and give context to the data must be preserved during the migration.
  • Accuracy of data transformation: Any transformations required as part of the migration process must yield the expected results without introducing unintended changes.
  • Risk management in data migration: A risk-based approach should be applied, similar to other phases of the system lifecycle. This includes conducting a data flow analysis to identify potential points of weakness during the transition and documenting all actions and evidence related to the migration to ensure compliance and traceability.

Electronic Data Archiving

Following migration, or as part of winding down a system, data archiving is necessary for storing data that is no longer actively used but still needs to be retained for long-term access. Developing an effective data archiving strategy involves:

  • Selection of appropriate storage solutions: The data may be stored on the same platform as the live system or transferred to a less expensive and slower storage solution. This decision will depend on the necessity of accessing the archived data for future reference, trending, or updating.
  • Ensuring data accessibility and protection: Even though the data is archived, it must remain accessible and protected as per regulatory requirements, ensuring that it can still be retrieved and read if necessary.

Data Destruction

In cases where data is no longer required or must be destroyed to comply with legal or regulatory standards, proper data destruction practices must be implemented. This process includes:

  • Complete removal of data: Ensuring that data is irretrievably destroyed from all storage media including live systems, backups, and archives.
  • Compliance with data protection regulations: Particularly for personal data, methods such as overwriting, physical destruction of hard disks, and secure shredding or incineration of paper records must be used to prevent any possibility of data recovery.

Documenting the Retirement Phase

Throughout the retirement phase, it is essential to document all processes and actions thoroughly. This documentation serves multiple purposes:

  • Regulatory compliance: Ensuring all actions are traceable and comply with industry regulations.
  • Audit readiness: Providing necessary documentation to support audits and inspections.
  • Knowledge preservation: Facilitating a smooth transition to new systems and providing references for future system retirements.

Computer System Validation Process V-Model

The V-Model is a structured approach used in Computer System Validation (CSV). This model emphasizes a step-by-step process where each stage is methodically handled to ensure the system meets all required specifications and regulatory standards.

User Requirements Specification (URS)

User Requirement Specification (URS) is fundamental in defining what the users expect the system to do. It includes detailed descriptions of all user requirements, focusing on what the system will be used for without detailing how the software will fulfill those needs. This document is the cornerstone for all future validation efforts, ensuring that the system is developed according to specific user needs and regulatory requirements.

Functional Specification

This document transitions from the ‘what’ to the ‘how.’ It details how the system’s requirements outlined in the URS will be implemented. The Functional Specification describes each function the system must perform and is pivotal for developers and testers to understand what needs to be built and validated.

Design Review

At this stage, the Design Review provides a more detailed view of the system. It outlines the architecture, including hardware and software, necessary to meet the functional specifications. This specification serves as a blueprint for the system’s construction, detailing the technical details and configurations needed to satisfy the functional requirements.

Configuration and / or Coding

With the design in place, configuration and coding begin. This phase involves setting up and/or customizing the software according to the design specification. For systems that require coding, this step includes writing, testing, and integrating the code as per the defined requirements.

Installation Qualification (IQ)

IQ is the initial step in the operational validation stages. It verifies that the software has been installed correctly and is accurately configured in its operating environment. This qualification checks that the system is installed according to the manufacturer’s specifications and that all system components are correctly cataloged and documented.

Operational Qualification (OQ)

OQ tests the system to ensure it performs as intended in all anticipated operating environments. This involves testing the system with all possible permutations of operating conditions to ensure it meets the required specifications outlined in the Functional Specification.

Performance Qualification (PQ)

The final testing phase, PQ, validates the system under actual or simulated real-world conditions. It demonstrates that the system consistently produces results meeting pre-determined acceptance criteria when used in the intended operational environment and by actual users.

Final Report

Once all qualifications are complete, the Final Report is compiled. This document summarizes the validation activities, results, and any deviations or anomalies observed during the testing phases. It provides a comprehensive review of the validation lifecycle, ensuring all stages are well-documented and traceable, and confirms that the system is ready for full-scale operational deployment.

RELATED ARTICLE: Qualification vs Validation

Challenges in Implementing CSV

Legacy systems often present significant hurdles in computer system validation due to their potential obsolescence and lack of contemporary documentation and testing protocols. These systems may require specialized validation strategies to ensure compliance with current regulations, despite their pre-validation existence. 

Moreover, the validation of these outdated systems is further complicated by their inherent non-compliance with modern standards, necessitating extensive efforts to bring them up to current regulatory expectations.

The process of implementing GAMP5, despite its benefits in enhancing regulatory compliance and process efficiency, introduces its own set of challenges. Organizations face difficulties such as the need for extensive documentation and the potential for long debates and rework due to inconsistent interpretation of standards. 

These challenges are exacerbated by decentralized governance and uncontrolled execution within many companies, leading to inconsistent project handling and unclear roles and responsibilities. Additionally, the variability in standards across different sites and departments can lead to significant inefficiencies and costs, further complicating the validation efforts.

Compounding these challenges is the rapid pace of technological advancement, which introduces complexities in validating increasingly sophisticated systems and software. This is often coupled with a shortage of skilled personnel, limited resources, and the need for robust cybersecurity measures to counteract heightened cyber threats and data breaches. 

Moreover, the management of changes during the validation process can disrupt established procedures and compromise compliance, highlighting the critical need for meticulous change control and re-qualification strategies.

Best Practices for Successful CSV Implementation

Some of the best practices for computer system validation include:

Develop a Strategic and Comprehensive Validation Plan

To ensure a successful Computer System Validation (CSV) implementation, it is essential to begin with a well-defined strategic plan. This plan should clearly state the validation’s goals and objectives, incorporating a thorough business and workflow analysis to understand the system’s impact on current operations. 

Following this, a detailed validation plan must be crafted, specifying the project’s scope, team members, their roles, and the requirements for system validation. This approach not only sets a clear roadmap but also aligns all team members toward common validation objectives.

Emphasize Documentation and Team Collaboration

Documentation plays a crucial role in CSV. Creating structured, clear, and comprehensive documentation that addresses redundancies, potential challenges, and ‘what-if’ scenarios is vital. 

This documentation should adhere to high-level guidance while promoting teamwork and clear communication among all departments involved, including IT, Human Resources, Quality, Validation, Production, and Maintenance. Ensuring that every staff member involved in the validation process is aware of Good Practice policies is critical to prevent breaches, loss of credibility, or hidden costs.

Integration of GAMP5 Principles and Automation Technologies

Incorporating GAMP5 principles into the CSV process enhances the approach to risk management, supplier relations, and system maintenance. These principles, which include risk management, lifecycle approach, supplier and internal audits, documentation and traceability, and change management, provide a robust framework for managing CSV processes effectively. 

Additionally, embracing automation and efficient technologies like cloud-based solutions can significantly reduce costs, improve flexibility, and streamline the validation process. Partnering with experienced vendors to develop a proactive plan for validation automation can save time and reduce costs, ensuring that the CSV implementation is both efficient and compliant.

FAQ – Computer System Validation

Can Electronic Records Generated by Computerized Systems Replace Paper Records?

Yes, electronic records can replace paper records if the system that generates them complies with regulatory requirements like FDA 21 CFR Part 11, which sets forth the criteria under which electronic records and electronic signatures are considered trustworthy, reliable, and equivalent to paper records.

How Does CSV Differ for Off-The-Shelf Software vs. Custom-Developed Software?

Validation of off-the-shelf software typically focuses on ensuring the software is configured appropriately and integrates well with existing systems. Custom-developed software requires extensive validation to ensure that all aspects of the software, including design and implementation, meet specific user requirements and function as intended.

How Often Should a Computerized System Be Revalidated?

Revalidation should occur whenever there are changes to the system, its environment, or operating conditions that could affect the system’s functionality or integrity. Additionally, periodic reviews should be conducted to ensure ongoing compliance, especially if the system is critical to product quality or regulatory requirements.

What Roles Does Risk Management Play in CSV?

Risk management in CSV involves identifying potential risks associated with the use of the computerized system that could impact product quality, data integrity, or regulatory compliance. Effective risk management helps prioritize validation efforts based on the severity and likelihood of potential risks.

Conclusion

Navigating the complex landscape of computerized systems validation – CSV demands a nuanced understanding of regulatory frameworks, coupled with a strategic approach towards planning, documentation, and execution. The challenges encountered during implementation underscore the necessity for robust risk management, ongoing vigilance in documentation practices, and the strategic integration of innovative technologies. 

By adhering to the principles and methodologies outlined, companies can not only ensure compliance but also fortify their operations against the rapid pace of technological advancements and evolving regulatory standards. As the importance of CSV continues to grow, the insights provided herein serve as a foundational blueprint for navigating its complexities successfully.

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