window.subscribe = async function (e) {
                                            e = e || window.event;
                                            e.preventDefault();
                                            try {
                                                let email = e.srcElement[0].value;
                                                let res = await $.post('/api/contacts', { email });
                                                $('.subscribe_letter').hide();
                                                $('.thank_subscribe').show();
                                                if (res && res.challenge) {
                                                    sessionStorage.setItem('challenge', JSON.stringify(res));
                                                    window.location.href = '/challenge';
                                                } else {
                                                    window.snaptr && window.snaptr('track', 'SUBSCRIBE');
                                                }
                                            } catch (error) {
                                                return false;
                                            }
                                        }