Design Pattern homework

var mod = (function(){

    function createContainer(id){
        var container = document.createElement("div");
        var parent = document.getElementById("wrapper");
        container.id = id;

        parent.appendChild(container);
    }

    function createSection(parent, title){
        var section = document.createElement("div");
        var sectionTitle = document.createElement("h1");
        sectionTitle.innerHTML = title;
        var parent = document.querySelector('#wrapper #' +  parent);

        section.appendChild(sectionTitle);
        parent.appendChild(section);
    }

    return {
        createContainer : createContainer,
        createSection : createSection,
    }
}());