code: public double setCount(F first, S second, double value) {
          Counter<S> counter = maps.get(first);
          if (counter == null) {
              counter = new Counter<S>();
              maps.put(first, counter);
          }
  
          return counter.setCount(second, value);
      }
docs: This method allows you to set counter value for a given first/second pair
  
  @param first
  @param second
  @param value
  @return