docs: def _new_token(self, chars=None, line_no=None):
          """ Appends new token to token stream.
  
              `chars`
                  List of token characters. Defaults to current token list.
              `line_no`
                  Line number for token. Defaults to current line number.
              """
  
          if not line_no:
              line_no = self._line_no
  
          if not chars:
              chars = self._token_chars
  
          if chars:
              # add new token
              self._tokens.append((line_no, ''.join(chars)))
              self._token_chars = []