code: def save_external_data(tensor, base_path):  # type: (TensorProto, Text) -> None
      
      info = ExternalDataInfo(tensor)
      external_data_file_path = os.path.join(base_path, info.location)
  
      # Retrieve the tensor's data from raw_data or load external file
      if not tensor.HasField("raw_data"):
          raise ValueError("raw_data field doesn't exist.")
  
      # Create file if it doesn't exist
      if not os.path.isfile(external_data_file_path):
          open(external_data_file_path, 'ab').close()
  
      # Open file for reading and writing at random locations ('r+b')
      with open(external_data_file_path, 'r+b') as data_file:
          data_file.seek(0, 2)
          if info.offset is not None:
              # Pad file to required offset if needed
              file_size = data_file.tell()
              if info.offset > file_size:
                  data_file.write(b"\0" * (info.offset - file_size))
  
              data_file.seek(info.offset)
          offset = data_file.tell()
          data_file.write(tensor.raw_data)
          set_external_data(tensor, info.location, offset, data_file.tell() - offset)
docs: Write tensor data to an external file according to information in the `external_data` field.
  
      @params
      tensor: Tensor object to be serialized
      base_path: System path of a folder where tensor data is to be stored