code: func (bj BinaryJSON) GetKeys() BinaryJSON {
  	count := bj.GetElemCount()
  	ret := make([]BinaryJSON, 0, count)
  	for i := 0; i < count; i++ {
  		ret = append(ret, CreateBinary(string(bj.objectGetKey(i))))
  	}
  	return buildBinaryArray(ret)
  }
docs: // GetKeys gets the keys of the object