original_string: public function participantsUserIds($userId = null)
      {
          $users = $this->participants()->lists('user_id');
  
          if ($userId) {
              $users[] = $userId;
          }
  
          return $users;
      }
code: public function participantsUserIds($userId = null)
      {
          $users = $this->participants()->lists('user_id');
  
          if ($userId) {
              $users[] = $userId;
          }
  
          return $users;
      }
code_tokens: public function participantsUserIds ( $ userId = null ) { $ users = $ this -> participants ( ) -> lists ( 'user_id' ) ; if ( $ userId ) { $ users [ ] = $ userId ; } return $ users ; }
docstring: Returns an array of user ids that are associated with the thread
  
  @param null $userId
  @return array
docstring_tokens: Returns an array of user ids that are associated with the thread