docs: def map_tokens_to_terms(self,list_tokens):
          """
          Maps a list of token ids to the corresponding term ids
          @type list_tokens: list
          @param list_tokens: list of token identifiers
          @rtype: list
          @return: list of term idenfitiers
          """
          if self.terms_for_token is None:
              self.terms_for_token = {}
              for term in self.get_terms():
                  termid = term.get_id()
                  token_ids = term.get_span().get_span_ids()
                  for tokid in token_ids:
                      if tokid not in self.terms_for_token:
                          self.terms_for_token[tokid] = [termid]
                      else:
                          self.terms_for_token[tokid].append(termid)
  
          ret = set()
          for my_id in list_tokens:
              term_ids = self.terms_for_token.get(my_id,[])
              ret |= set(term_ids)
          return sorted(list(ret))