code: func setLabel(labels map[appctypes.ACIdentifier]string, key, val string) {
  	if key != "" && val != "" {
  		labels[*appctypes.MustACIdentifier(key)] = val
  	}
  }
docs: // setLabel sets the label entries associated with non-empty key
  // to the single non-empty value. It replaces any existing values
  // associated with key.