code: public boolean containsTagHandler(String ns, String localName)
      {
          return containsNamespace(ns) && _factories.containsKey(localName);
      }
docs: /*
  (non-Javadoc)
  
  @see org.apache.myfaces.view.facelets.tag.TagLibrary#containsTagHandler(java.lang.String, java.lang.String)