var credit = 0;
function main_menu(){  //the main menu of the vending machine
    console.log('#-*-*-*-*-*-*-*-*-*-#');
    console.log('    Main  Menu');
    console.log('|-*-*-*-*-*-*-*-*-*-|');
    console.log('    Credit'+ credit);
    console.log('#-*-*-*-*-*-*-*-*-*-#');

    for (var idx = 0; idx < options.length; idx++) {
        console.log(idx + ': ' + options[idx]);
    }

    var choice = readline.question('Choice: ');
    if(choice == 0){
        console.log('You chose option ' + choice);
        products_menu();
    }
    if(choice == 1){
        add_credit();
    }
    if(choice == 2){
        refund();
    }


}
function add_credit(){
    var add = readline.question('How much credit would you like to add?: ');
    credit += add_credit;
    console.log('You added ' + add);
    main_menu();
}