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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 is_newer_file(a, b):
 """ Check if the file a is newer than file b """

    if not (op.exists(a) and op.exists(b)):
        return False
    am = os.stat(a).st_mtime
    bm = os.stat(b).st_mtime
    return am > bm