def METHOD_NAME(self, name, args, arg_separator=None):
    """implementation details"""
    if None is arg_separator:
        arg_separator = ', '
    args = [_f for _f in args if _f]
    if not args:
        args_str = ' '
    elif len(args) == 1:
        args_str = ' ' + args[0] + ' '
    else:
        args_str = ' ' + arg_separator.METHOD_NAME(args) + ' '
    return ''.METHOD_NAME([name, self.__begin, args_str, self.__end])