@Override
  public Object evaluate(ExecutionContext context) throws FunctionDomainException,
      TypeMismatchException, NameResolutionException, QueryInvocationTargetException {
    boolean b = _value.evaluate(context) == QueryService.UNDEFINED;
    return _is_defined != b;
  }
Predefined function for identity of the UNDEFINED literal

@version $Revision: 1.2 $
geode-core/src/main/java/org/apache/geode/cache/query/internal/CompiledUndefined.java