code: public function findFirstAction($parameters)
      {
          $slot = $this->findFirstSlot($parameters);
          if (isset($slot) && isset($slot['content'])) {
              return $slot['content'];
          }
  
          return;
      }
docs: Searches the call list for a matching parameter set. Returned by reference.
  
  @param array $parameters    Parameters to search by without wildcards.
  
  @return object              Object held in the first matching slot, otherwise null.