code: public function possibleModuleSets()
      {
          $s = ['' => '(core)'];
          foreach (Yii::$app->extensions as $id => $ext) {
              if (!isset($ext['bootstrap'])) {
                  continue;
              }
              $bsClass = $ext['bootstrap'];
              $bs = new $bsClass();
              if ($bs instanceof ModuleSetExtension) {
                  $s[$id] = $id;
              }
          }
  
          return $s;
      }
docs: [[@doctodo method_description:possibleModuleSets]].
  
  @return [[@doctodo return_type:possibleModuleSets]] [[@doctodo return_description:possibleModuleSets]]