public double getCount(F first, S second) {
        Counter<S> counter = maps.get(first);
        if (counter == null)
            return 0.0;

        return counter.getCount(second);
    }
public double getCount ( F first , S second ) { Counter < S > counter = maps . get ( first ) ; if ( counter == null ) return 0.0 ; return counter . getCount ( second ) ; }
This method returns counts for a given first/second pair

@param first
@param second
@return