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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def worker_task(work_item, config):
 """The celery task which performs a single mutation and runs a test suite. This runs `cosmic-ray worker` in a subprocess and returns the results, passing `config` to it via stdin. Args: work_item: A dict describing a WorkItem. config: The configuration to use for the test execution. Returns: An updated WorkItem """

    global _workspace

    _ensure_workspace(config)

    result = worker(
        work_item.module_path,
        config.python_version,
        work_item.operator_name,
        work_item.occurrence,
        config.test_command,
        config.timeout)
    return work_item.job_id, result