code: def write_external_data_tensors(model, filepath):  # type: (ModelProto, Text) -> ModelProto
      
      for tensor in _get_all_tensors(model):
          if uses_external_data(tensor):
              save_external_data(tensor, filepath)
              tensor.ClearField(str('raw_data'))
  
      return model
docs: Write external data of all tensors to files on disk.
  
      Note: This function also strips basepath information from all tensors' external_data fields.
  
      @params
      model: Model object which is the source of tensors to serialize.
      filepath: System path to the directory which should be treated as base path for external data.
  
      @return
      The modified model object.