private static function flattenArgument (&$value, $key) {
        if ($value instanceof Closure) {
            $closureReflection = new ReflectionFunction($value);
            $value = sprintf('(Closure at %s:%s)', $closureReflection->getFileName(), $closureReflection->getStartLine());
        } elseif (is_object($value)) {
            $value = sprintf('object(%s)', get_class($value));
        } elseif (is_resource($value)) {
            $value = sprintf('resource(%s)', get_resource_type($value));
        }
    }