code: function _done (cb, message) {
    var valid = false
  
    if (typeof message === 'string') {
      message = [message]
    } else if (Object.prototype.toString.call(message) === '[object Array]') {
      if (message.length === 0) {
        valid = true
      }
    } else {
      valid = true
    }
  
    if (isFunction(cb)) {
      if (valid) {
        cb(valid, [])
      } else {
        cb(valid, message)
      }
    }
  
    return valid
  }
docs: Formats error messages, calls the callback
  @method done
  @private
  @param cb {Function} callback
  @param [message] {Function} callback
  @return {Boolean} is the object valid or not?