code: public function getActiveFormNext()
      {
          $key = null;
          $actualKey = $this->getActiveFormActual();
          if (isset($actualKey)) {
              $forms = array_keys($this->forms);
              $formsFlip =  array_flip($forms);
              $index = $formsFlip[$actualKey];
              if ($index < count($forms) - 1) {
                  $key = $forms[$index+1];
              }
          }
          return $key;
      }
docs: Gets the form after the actual active
  @return null