def __init__(self, id_filename=Config.group_sub_id_file):
        """
        Constructor method.
        Attempt to read and parse the file named id_filename. An empty
        map is returned if id_filename is None.
        """

        super().__init__()
        if id_filename:
            self.read(id_filename)
def __init__ ( self , id_filename = Config . group_sub_id_file ) : super ( ) . __init__ ( ) if id_filename : self . read ( id_filename )
Constructor method.
        Attempt to read and parse the file named id_filename. An empty
        map is returned if id_filename is None.