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    /**
     * Get an instance of a ModuleFrontController
     *
     * @param string $controller The name of the controller, it must be declared in your module
     *
     * @return ModuleFrontController Instance of the controller
     */
    public function getModuleFrontControllerInstance($controller)
    {
        // Check this controller is allowed
        if (!in_array($controller, $this->controllers)) {
            throw new PrestaShopException(sprintf('This controller %s is not declared in this module', Tools::safeOutput($controller)));
        }

        // Include the controller file
        require_once __DIR__ . '/controllers/front/' . $controller . '.php';

        // Build dynamically the controller name
        $controller_name = $controller . 'ModuleFrontController';

        // Instantiate controller
        $controller = new $controller_name($this, __FILE__, $this->_path);

        // Return the controller
        return $controller;
    }
    
    public function weirdFunction()
    {
        $controller = $this->getModuleFrontControllerInstance('myFrontController');
        
        return $controller->myOwnProcessInModuleFrontController();
    }

Try somethings like that