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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 _file_and_exists(val, input_files):
 """Check if an input is a file and exists. Checks both locally (staged) and from input files (re-passed but never localized). """

    return ((os.path.exists(val) and os.path.isfile(val)) or
            val in input_files)