code: def _ReadDefinitionFile(self, filename):
      
      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)
docs: 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.