code: public function setState($key, $value)
      {
          return Yii::$app->webState->set($this->stateKeyName($key), $value);
      }
docs: Set state.
  
  @param [[@doctodo param_type:key]]   $key   [[@doctodo param_description:key]]
  @param [[@doctodo param_type:value]] $value [[@doctodo param_description:value]]
  
  @return [[@doctodo return_type:setState]] [[@doctodo return_description:setState]]