code: public boolean elementAvailable(String ns, String elemName)
            throws javax.xml.transform.TransformerException
    {
      boolean isAvailable = false;
      if (null != ns)
      {
        ExtensionHandler extNS = 
                 (ExtensionHandler) m_extensionFunctionNamespaces.get(ns);
        if (extNS != null) // defensive
          isAvailable = extNS.isElementAvailable(elemName);
      } 
      return isAvailable;        
    }
docs: Execute the element-available() function.
  @param ns       the URI of namespace in which the function is needed
  @param elemName name of element being tested
  
  @return whether the given element is available or not.
  
  @throws javax.xml.transform.TransformerException