Multiple routes with the same anonymous callback using Slim Framework

How can I define multiple routes that use the same anonymous callback?

$app->get('/first_route',function()
{
   //Do stuff
});
$app->get('/second_route',function()
{
   //Do same stuff
});

I know I can use a reference to a function which would work, but I'd prefer a solution for using the anonymous function to be consistent with the rest of the codebase.

So basically, what I'm looking for is a way of doing something like this:

$app->get(['/first_route','/second_route'],function()
{
       //Do same stuff for both routes
});

~ OR ~

$app->get('/first_route',function() use($app)
{
   $app->get('/second_route');//Without redirect
});

Thank you.