call to set all tensors as external data. save_model saves all the tensors data as external data after calling this function.
    @params
    model: ModelProto to be converted.
    all_tensors_to_one_file: If true, save all tensors to one external file specified by location.
                             If false, save each tensor to a file named with the tensor name.
    location: specify the external file that all tensors to save to.
              If not specified, will use the model name.

def convert_model_to_external_data(model, all_tensors_to_one_file=True, location=None):
    # type: (ModelProto, bool, Optional[Text]) -> None
    """
    call to set all tensors as external data. save_model saves all the tensors data as external data after calling this function.
    @params
    model: ModelProto to be converted.
    all_tensors_to_one_file: If true, save all tensors to one external file specified by location.
                             If false, save each tensor to a file named with the tensor name.
    location: specify the external file that all tensors to save to.
              If not specified, will use the model name.
    """
    if all_tensors_to_one_file:
        file_name = Text(uuid.uuid1())
        if location:
            file_name = location
        for tensor in _get_all_tensors(model):
            set_external_data(tensor, file_name)
    else:
        for tensor in _get_all_tensors(model):
            set_external_data(tensor, tensor.name)