def _ReadDefinitionFile(self, filename):
    """Reads a dtFabric definition file.

    Args:
      filename (str): name of the dtFabric definition file.

    Returns:
      dtfabric.DataTypeFabric: data type fabric which contains the data format
          data type maps of the data type definition, such as a structure, that
          can be mapped onto binary data or None if no filename is provided.
    """
    if not filename:
      return None

    path = os.path.join(self._DEFINITION_FILES_PATH, filename)
    with open(path, 'rb') as file_object:
      definition = file_object.read()

    return dtfabric_fabric.DataTypeFabric(yaml_definition=definition)
Reads a dtFabric definition file.

    Args:
      filename (str): name of the dtFabric definition file.

    Returns:
      dtfabric.DataTypeFabric: data type fabric which contains the data format
          data type maps of the data type definition, such as a structure, that
          can be mapped onto binary data or None if no filename is provided.