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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 GetOptions(self):
 """Retrieves descriptor options. This method returns the options set or creates the default options for the descriptor. """

    if self._options:
      return self._options
    from google.protobuf import descriptor_pb2
    try:
      options_class = getattr(descriptor_pb2, self._options_class_name)
    except AttributeError:
      raise RuntimeError('Unknown options class name %s!' %
                         (self._options_class_name))
    self._options = options_class()
    return self._options