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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 get_requirement_files(args=None):
 """ Get the "best" requirements file we can find """

    if args and args.input_filename:
        return [args.input_filename]

    paths = []
    for regex in settings.REQUIREMENTS_SOURCE_GLOBS:
        paths.extend(glob.glob(regex))
    return paths