Yuffster

function createUser(username, callback) {
    var connection = DatabaseClient.connect();
    var users = connection.collection('users');
    var query = users.query({username: username});
    return query.then(function(existing){
        if(existing) throw new Error("User already exists: " + username);
        else return users.create({username: username});
    }).fin(function(connection){  return connection.call('close'); });
}

Yuffster

function createUser(username, callback) {
    var connection = DatabaseClient.connect();
    var users = connection.call('collection', 'users');
    var query = users.call('query', {username: username});
    return query.then(function(existing){
        if(existing) throw new Error("User already exists: " + username);
        else return users.call('create', {username: username});
    }).fin(function(connection){  return connection.call('close'); });
}

Yuffster

(function(){
	
	function check(e, selector, fn){
		var target    = e.target,
			els       = this.getElements(selector),
			isOverOut = /^(mouseover|mouseout)$/.test(e.type);
		
		for (var i = els.length; i--; ){
			var el = els[i];
			if (el == target || el.hasChild(target)){