code: def tokens(self, tokenset='internal'):
          
          toks = self.get('tokens', {}).get(tokenset)
          if toks is not None:
              if isinstance(toks, stringtypes):
                  toks = YyTokenLattice.from_string(toks)
              elif isinstance(toks, Sequence):
                  toks = YyTokenLattice.from_list(toks)
          return toks
docs: Deserialize and return a YyTokenLattice object for the
          initial or internal token set, if provided, from the YY
          format or the JSON-formatted data; otherwise return the
          original string.
  
          Args:
              tokenset (str): return `'initial'` or `'internal'` tokens
                  (default: `'internal'`)
          Returns:
              :class:`YyTokenLattice`