code: function toString()
      {
  
          // Generate standard field string
          $fields = "";
          if (isset($this->fields)) {
              foreach ($this->fields as $index => $value) {
                  $fields .= $index . "=" . $value . ",";
              }
              $fields = rtrim($fields, ',');
          }
  
          return "Mailing [id=" . $this->id . ", fields={" . $fields . "}]";
      }
docs: Human readable representation of this wrapper.
  
  @return \em string
  A human readable version of the mailing.