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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 _read_routine_metadata(self):
 """ Returns the metadata of stored routines. :rtype: dict """

        metadata = {}
        if os.path.isfile(self._metadata_filename):
            with open(self._metadata_filename, 'r') as file:
                metadata = json.load(file)

        return metadata