function solve() {
        let nextId = "depot";
        let nextStop = "";
        function depart() {
            $.ajax({
                method: 'GET',
                url: `https://judgetests.firebaseio.com/schedule/${nextId}/.json`,
                success: function (data) {
                    console.log(data);
                    $('#info span').text(`Next stop ${data.name}`);
                    $('#depart').prop("disabled", true);
                    $('#arrive').prop("disabled", false);
                    nextId = data.next;
                    nextStop = data.name;
                },
                error: function () {
                    $('#info span').text(`Error`);
                    $('#depart').prop("disabled", true);
                    $('#arrive').prop("disabled", true);
                }
            });
        }

        function arrive() {
            $('#info span').text(`Arriving at ${nextStop}`);
            $('#depart').prop("disabled", false);
            $('#arrive').prop("disabled", true);
        }
        return {
            depart,
            arrive
        };
    }