all signatures. Unlike ``set_parse_action``,
        functions passed to ``add_condition`` need to return boolean success/fail of the condition.

        Optional keyword arguments:

        - ``message`` = define a custom message to be used in the raised exception
        - ``fatal`` = if True, will raise ParseFatalException to stop parsing immediately; otherwise will raise
          ParseException
        - ``call_during_try`` = boolean to indicate if this method should be called during internal tryParse calls,
          default=False

        Example::

            integer = Word(nums).set_parse_action(lambda toks: int(toks[0]))
            year_int = integer.copy()
            year_int.add_condition(lambda toks: toks[0] >= 2000, message="Only support years 2000 and later")
            date_str = year_int + '/' + integer + '/' + integer

            result = date_str.parse_string("1999/12/31")  # -> Exception: Only support years 2000 and later (at char 0),
                                                                         (line:1, col:1)
        rĶ