code: def get_operation_mtf_dimension_names(self, operation_name):
      
      mtf_dimension_names = set()
      for tensor_name in self.get_operation_input_names(operation_name):
        mtf_dimension_names.update(self.get_tensor_mtf_dimension_names(
            tensor_name))
      for tensor_name in self.get_operation_output_names(operation_name):
        mtf_dimension_names.update(self.get_tensor_mtf_dimension_names(
            tensor_name))
      return mtf_dimension_names
docs: The Mesh TensorFlow dimensions associated with an operation.
  
      Args:
        operation_name: a string, name of an operation in the graph.
  
      Returns:
        a set(string), the names of Mesh TensorFlow dimensions.