@classmethod
def expected_string(cls, dialect=None, called_from=None):
    """Return the expected string for this segment.

        This is never going to be called on an _instance_
        but rather on the class, as part of a grammar, and therefore
        as part of the matching phase. So we use the match grammar.
        """
    return cls._match_grammar().expected_string(dialect=dialect,
        called_from=called_from)
