code: def id2word(self, xs):
          
          if isinstance(xs, list):
              return [self._id2word[x] for x in xs]
          return self._id2word[xs]
docs: Map id(s) to word(s)
  
          Parameters
          ----------
          xs : int
              id or a list of ids
  
          Returns
          -------
          str or list
              word or a list of words