def and_next(e):
    """
    Create a PEG function for positive lookahead.
    """
    def match_and_next(s, grm=None, pos=0):
        try:
            e(s, grm, pos)
        except PegreError as ex:
            raise PegreError('Positive lookahead failed', pos)
        else:
            return PegreResult(s, Ignore, (pos, pos))
    return match_and_next