function logUser(userList, user) {

if(!userList.includes(user)) {

userList.push(user);

}

}

function numUsers(userList) {

return userLeft.length;

}

function userLeft(userList, user) {

const userIndex = userList.indexOf(user);

if (userIndex >= 0) {

userList.splice(userIndex, 1);

}

}

function runSite() {

// Your user list for your website

const users = [];

// Simulate user viewing your site

logUser(users, 'user1');

logUser(users, 'user2');

logUser(users, 'user3');

// User left your website

userLeft(users, 'user2');

// More user goes to your website

logUser(users, 'user4');

logUser(users, 'user4');

logUser(users, 'user5');

logUser(users, 'user6');

// More user left your website

userLeft(users, 'user1');

userLeft(users, 'user4');

userLeft(users, 'user2');

console.log('Current user: ', users.join(', '));

}

runSite();