public function _normalizeCallable($callable)
    {
        // Closure remains as such
        if ($callable instanceof Closure) {
            return $callable;
        }

        // Invocable objects take precedence over stringable ones
        if (!(is_object($callable) && is_callable($callable))) {
            try {
                // Strings that don't identify methods get normalized and returned
                $callable = $this->_normalizeString($callable);
                if (strpos($callable, '::', 1) === false) {
                    return $callable;
                }
            } catch (InvalidArgumentException $e) {
                // Continue
            }
        }

        // Everything else is a method
        return $this->_normalizeMethodCallable($callable);
    }