code: public function getState($key, $default = null)
      {
          return Yii::$app->webState->get($this->stateKeyName($key), $default);
      }
docs: Get state.
  
  @param [[@doctodo param_type:key]]     $key     [[@doctodo param_description:key]]
  @param [[@doctodo param_type:default]] $default [[@doctodo param_description:default]] [optional]
  
  @return [[@doctodo return_type:getState]] [[@doctodo return_description:getState]]