How to use the mechanicalsoup.LinkNotFoundError function in MechanicalSoup

def open_legacy_httpbin(browser, httpbin):
    """Opens the start page of httpbin (given as a fixture). Tries the
    legacy page (available only on recent versions of httpbin), and if
    it fails fall back to the main page (which is JavaScript-only in
    recent versions of httpbin hence usable for us only on old
    versions).
    """
    try:
        response = browser.open(httpbin + "/legacy")
        if response.status_code == 404:
            # The line above may or may not have raised the exception
            # depending on raise_on_404. Raise it unconditionally now.
            raise mechanicalsoup.LinkNotFoundError()
    except mechanicalsoup.LinkNotFoundError:
        browser.open(httpbin.url)

def test_select_form_nr():
    """Test the nr option of select_form."""
    forms = """<form id="a"></form><form id="b"></form><form id="c"></form>"""
    with mechanicalsoup.StatefulBrowser() as browser:
        browser.open_fake_page(forms)
        form = browser.select_form()
        assert form.form['id'] == "a"
        form = browser.select_form(nr=1)
        assert form.form['id'] == "b"
        form = browser.select_form(nr=2)
        assert form.form['id'] == "c"
        with pytest.raises(mechanicalsoup.LinkNotFoundError):
            browser.select_form(nr=3)

def test_launch_browser(mocker):
    browser = mechanicalsoup.StatefulBrowser()
    browser.set_debug(True)
    browser.open_fake_page('')
    mocker.patch('webbrowser.open')
    with pytest.raises(mechanicalsoup.LinkNotFoundError):
        browser.follow_link('nosuchlink')
    # mock.assert_called_once() not available on some versions :-(
    assert webbrowser.open.call_count == 1
    mocker.resetall()
    with pytest.raises(mechanicalsoup.LinkNotFoundError):
        browser.select_form('nosuchlink')
    # mock.assert_called_once() not available on some versions :-(
    assert webbrowser.open.call_count == 1

def _MFACheck(br, email, soup):
        Log('MFA, DCQ or Captcha form')
        uni_soup = soup.__unicode__()
        try:
            form = br.select_form('form[name="signIn"]')
        except mechanicalsoup.LinkNotFoundError:
            form = br.select_form()

        if 'auth-mfa-form' in uni_soup:
            msg = soup.find('form', attrs={'id': 'auth-mfa-form'})
            msgtxt = msg.p.get_text(strip=True)
            kb = xbmc.Keyboard('', msgtxt)
            kb.doModal()
            if kb.isConfirmed() and kb.getText():
                br['otpCode'] = kb.getText()
            else:
                return None
        elif 'ap_dcq_form' in uni_soup:
            msg = soup.find('div', attrs={'id': 'message_warning'})
            g.dialog.ok(g.__plugin__, msg.p.get_text(strip=True))
            dcq = soup.find('div', attrs={'id': 'ap_dcq1a_pagelet'})
            dcq_title = dcq.find('div', attrs={'id': 'ap_dcq1a_pagelet_title'}).get_text(strip=True)

def test_404(httpbin):
    browser = mechanicalsoup.Browser(raise_on_404=True)
    with pytest.raises(mechanicalsoup.LinkNotFoundError):
        resp = browser.get(httpbin + "/nosuchpage")
    resp = browser.get(httpbin.url)
    assert resp.status_code == 200

form['lastname'] = self._settings.get('user', "lastname")
        form['email'] = self._change_email_provider(self._settings.get('user', "email"), '@gmail.com')
        form['phonenumber'] = self._settings.get('user', "phonenumber")
        form['companyname'] = self._settings.get('user', "companyname")
        form['address1'] = self._settings.get('address', "address")
        form['city'] = self._settings.get('address', "city")
        form['state'] = self._settings.get('address', "state")
        form['postcode'] = self._settings.get('address', "zipcode")
        form['country'] = self._settings.get('address', 'countrycode')
        form['password'] = self._settings.get('user', "password")
        form['password2'] = self._settings.get('user', "password")
        form['paymentmethod'] = payment_method.lower()

        try:
            form['accepttos'] = True  # Attempt to accept the terms and conditions
        except LinkNotFoundError:
            pass

        page = self._browser.submit_selected()
        # Error handling
        if 'checkout' in page.url:
            soup = BeautifulSoup(page.text, 'lxml')
            errors = soup.find('div', {'class': errorbox_class}).text
            print((errors.strip()))
            sys.exit(2)

        return page

def server_form(self, user_settings):
        """
        Fills in the form containing server configuration.
        :param user_settings: settings
        :return: 
        """
        self.select_form_id(self.br, 'frmConfigureProduct')
        self.fill_in_server_form(self.br.form, user_settings, nameservers=False)
        try:
            self.br.form['configoption[20]'] = ['53']  # Paris
            self.br.form['configoption[2]'] = ['13']
        except LinkNotFoundError:
            self.br.form['configoption[19]'] = ['51']  # Paris
            self.br.form['configoption[16]'] = ['41']  # Ubuntu 14.04
        self.br.submit()

xbmc.executebuiltin('Addon.OpenSettings({})'.format(var.addon.getAddonInfo('id')))
            return False

    if password:
        cj = requests.cookies.RequestsCookieJar()
        br = mechanicalsoup.StatefulBrowser(soup_config={'features': 'html.parser'})
        br.set_cookiejar(cj)
        br.session.verify = var.verifySsl
        caperr = -5
        while caperr:
            Log('Connect to SignIn Page {} attempts left'.format(-caperr))
            br.session.headers.update({'User-Agent': getConfig('UserAgent')})
            br.open(BaseUrl + '/gp/aw/si.html')
            try:
                form = br.select_form('form[name="signIn"]')
            except mechanicalsoup.LinkNotFoundError:
                getUA(True)
                caperr += 1
                WriteLog(str(br.get_current_page()), 'login-si')
                xbmc.sleep(randint(750, 1500))
            else:
                break
        else:
            Dialog.ok(getString(30200), getString(30213))
            return False

        form.set_input({'email': email, 'password': password})

        br.session.headers.update({'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
                                   'Accept-Encoding': 'gzip, deflate',
                                   'Accept-Language': 'de,en-US;q=0.8,en;q=0.6',
                                   'Cache-Control': 'max-age=0',

form.form['action'] = 'https://crowncloud.net/clients/cart.php'
            print("Frm1")
            # form.form['method'] = 'post'
        except LinkNotFoundError:
            print("Frm2")
            form = self._browser.select_form('form#frmConfigureProduct')
            self._fill_server_form()

        form['billingcycle'] = 'monthly'
        form['configoption[1]'] = '56'
        form['configoption[8]'] = '52'

        try:  # The extra bandwidth option is not always available
            form['configoption[9]'] = '0'
        except LinkNotFoundError:
            pass

        return self._browser.submit_selected()