def pair_ahead(self, table):
    if ((self.index + 1) < len(self.source)):
        return (self.source[self.index:(self.index + 2)] in table)
    return False
def pair_ahead(self, table):
    if ((self.index + 1) < len(self.source)):
        return (self.source[self.index:(self.index + 2)] in table)
    return False