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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 _MergeIdenticalCaseInsensitive(self, a, b):
 """Tries to merge two strings. The string are required to be the same ignoring case. The second string is always used as the merged value. Args: a: The first string. b: The second string. Returns: The merged string. This is equal to the second string. Raises: MergeError: The strings were not the same ignoring case. """

    if a.lower() != b.lower():
      raise MergeError("values must be the same (case insensitive) "
                       "('%s' vs '%s')" % (transitfeed.EncodeUnicode(a),
                                           transitfeed.EncodeUnicode(b)))
    return b