code: public String getNamespaceForPrefix(String prefix, org.w3c.dom.Node context)
    {
      this.error(XSLTErrorResources.ER_CANT_RESOLVE_NSPREFIX, null);
  
      return null;
    }
docs: Fullfill the PrefixResolver interface.  Calling this for this class
  will throw an error.
  
  @param prefix The prefix to look up, which may be an empty string ("")
  for the default Namespace.
  @param context The node context from which to look up the URI.
  
  @return null if the error listener does not choose to throw an exception.