def _increment(self, n=1):
        """Move forward n tokens in the stream."""
        if self._cur_position >= self.num_tokens-1:
            self._cur_positon = self.num_tokens - 1
            self._finished = True
        else:
            self._cur_position += n
def _increment ( self , n = 1 ) : if self . _cur_position >= self . num_tokens - 1 : self . _cur_positon = self . num_tokens - 1 self . _finished = True else : self . _cur_position += n
Move forward n tokens in the stream.