code: function _isUniqueId(currentId, newId) {
  	if (
  		newId !== undefined &&
  		currentId !== newId &&
  		_belongToAStoredAmbush(newId)
  	) {
  		logger('AMBUSH_PROVIDED_ID_ALREADY_EXIST');
  		return false;
  	}
  
  	return true;
  }
docs: Validates an id doesn't belong to an already stored ambush function. When updating
  an ambush function id check if the new id it's already in use.
  
  @param {string} currentId Ambush function current id.
  @param {string} newId Ambush function new id.
  @returns {bool} If it already exist or not.