code: public Match<E> lookingAt(List<E> tokens, int start) {
          return auto.lookingAt(tokens, start);
      }
docs: Determine if the regular expression matches the supplied tokens,
  starting at the specified index.
  
  @param tokens the list of tokens to match.
  @param start the index where the match should begin.
  @return an object representing the match, or null if no match is found.