def _clean_up_key(self, key):
        """
        Returns the key string with no naughty characters.
        """
        for n in self.naughty: key = key.replace(n, '_')
        return key
def _clean_up_key ( self , key ) : for n in self . naughty : key = key . replace ( n , '_' ) return key
Returns the key string with no naughty characters.