if pref.string(forKey: "username") != nil && pref.string(forKey: "password") != nil {
        let user = self.pref.string(forKey: "username")
        let pass = self.pref.string(forKey: "password")
        self.eUser.text = user
        self.ePass.text = pass
        login_account()
    }

if response == "Invalid credentials" {
        DispatchQueue.main.async(execute: {
            NVActivityIndicatorPresenter.sharedInstance.stopAnimating()
            self.show_alert(response)
        })
    } else {
        DispatchQueue.main.async(execute: {
            NVActivityIndicatorPresenter.sharedInstance.stopAnimating()
            self.saveCredentials(username: user, password: pass)
            self.performSegue(withIdentifier: "test_segue", sender: self)
        })
    }