code: func Keys(o *Object) []string {
  	if o == nil || o == Undefined {
  		return nil
  	}
  	a := Global.Get("Object").Call("keys", o)
  	s := make([]string, a.Length())
  	for i := 0; i < a.Length(); i++ {
  		s[i] = a.Index(i).String()
  	}
  	return s
  }
docs: // Keys returns the keys of the given JavaScript object.