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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 patch():
 """Patch PynamoDB so it generates subsegements when calling DynamoDB."""

    import pynamodb

    if hasattr(botocore.vendored.requests.sessions, '_xray_enabled'):
        return
    setattr(botocore.vendored.requests.sessions, '_xray_enabled', True)

    wrapt.wrap_function_wrapper(
        'botocore.vendored.requests.sessions',
        'Session.send',
        _xray_traced_pynamodb,
    )