code: protected function getValueCreator($value)
      {
          if (is_string($value) && class_exists($value)) {
              return function($injector) use($value) { return $injector->getInstance($value); };
          }
  
          return function() use($value) { return $value; };
      }
docs: creates a closure which returns the given value
  
  @param   mixed $value
  @return  \Closure