code: public int getRank(E element) {
  
      Ranking ranking = this.map.get(element);
      if (ranking == null) {
        return 0;
      } else {
        return ranking.rank;
      }
    }
docs: This method gets the current rank for the given {@code element}. The rank is in the range from
  {@link #RANK_UNACCEPTABLE -1} to {@link Integer#MAX_VALUE}. If the {@code element} has no rank, a value of
  {@code 0} will be returned.
  
  @see #RANK_UNACCEPTABLE
  @see #addRank(Object, int)
  
  @param element is the element for which the rank is requested.
  @return the current rank of the given {@code element}.