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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 _MergeIdentical(self, a, b):
 """Tries to merge two values. The values are required to be identical. Args: a: The first value. b: The second value. Returns: The trivially merged value. Raises: MergeError: The values were not identical. """

    if a != b:
      raise MergeError("values must be identical ('%s' vs '%s')" %
                       (transitfeed.EncodeUnicode(a),
                        transitfeed.EncodeUnicode(b)))
    return b