src/StaticApplicationAbstract.php
public function addMiddleware($middleware) {
        if (!is_callable($middleware) && !is_array($middleware)) {
            throw new InvalidArgumentException("Middleware must be a valid callable");
        } else {
            $this->middleware[] = $middleware;
        }
    }
public function addMiddleware($middleware) {
        if (!is_callable($middleware) && !is_array($middleware)) {
            throw new InvalidArgumentException("Middleware must be a valid callable");
        } else {
            $this->middleware[] = $middleware;
        }
    }
Add middleware to application
@param callable|array $middleware