src/Router.php
public function apply($middleware)
    {
        foreach (func_get_args() as $mw) {
            $this->_scopes[0]->apply($mw);
        }
        return $this;
    }
public function apply($middleware)
    {
        foreach (func_get_args() as $mw) {
            $this->_scopes[0]->apply($mw);
        }
        return $this;
    }
Adds a middleware to the list of middleware.

@param object|Closure A callable middleware.