code: private function inspectClosure($subject)
      {
          $reflection = new ReflectionFunction($subject);
          $params = array_map(function($param) {
              return ($param->isPassedByReference() ? '&$' : '$').$param->name;
          }, $reflection->getParameters());
          $this->result[] = 'Closure ('.implode(", ", $params).') { ... }'."\n";
      }
docs: Inspired by: http://www.metashock.de/2013/05/dump-source-code-of-closure-in-php/