throws Throwable
  public Value get_parent_class(Env env, @ReadOnly Value value)    throws Throwable  {    if (value instanceof ObjectValue) {      ObjectValue obj = (ObjectValue) value;      String parent = obj.getParentName();      if (parent != null)	return new StringValueImpl(parent);    }    else if (value instanceof StringValue) {      String className = value.toString();      QuercusClass cl = env.findClass(className);      if (cl != null) {	String parent = cl.getParentName();	if (parent != null)	  return new StringValueImpl(parent);      }    }    return BooleanValue.FALSE;  }