code: func decodeValue(rawKV interface{}) error {
  	rawMap, ok := rawKV.(map[string]interface{})
  	if !ok {
  		return fmt.Errorf("unexpected raw KV type: %T", rawKV)
  	}
  	for k, v := range rawMap {
  		switch strings.ToLower(k) {
  		case "value":
  			// Leave the byte slice nil if we have a nil
  			// value.
  			if v == nil {
  				return nil
  			}
  
  			// Otherwise, base64 decode it.
  			s, ok := v.(string)
  			if !ok {
  				return fmt.Errorf("unexpected value type: %T", v)
  			}
  			decoded, err := base64.StdEncoding.DecodeString(s)
  			if err != nil {
  				return fmt.Errorf("failed to decode value: %v", err)
  			}
  			rawMap[k] = decoded
  			return nil
  		}
  	}
  	return nil
  }
docs: // decodeValue decodes the value member of the given operation.