code: public static final <X> Function<X,Boolean> isNotNullBy(final IFunction<X,?> by) {
          return FnFunc.chain(by, IS_NOT_NULL);
      }
docs: <p>
  Determines whether the result of executing the
  specified function on the target object is null or not.
  </p>
  
  @return false if the function result is null, true if not.