code: public SetBase<T> forEach($.Visitor<? super T> visitor) throws $.Break {
          for (T t : this) {
              try {
                  visitor.apply(t);
              } catch (NotAppliedException e) {
                  // ignore
              }
          }
          return this;
      }
docs: Sub class could override this method to implement iterating in parallel.
  
  <p>The iterating support partial function visitor by ignoring the
  {@link org.osgl.exception.NotAppliedException} thrown out by visitor's apply
  method call</p>
  
  @param visitor the visitor
  @throws $.Break if visitor needs to terminate the iteration