function createList(isCollapsed) {
        var listElement = (options.orderedList) ? 'ol' : 'ul'
        var list = document.createElement(listElement)
        var classes = options.listClass +
            SPACE_CHAR + options.extraListClasses
        if (isCollapsed) {
            classes += SPACE_CHAR + options.collapsibleClass
            classes += SPACE_CHAR + options.isCollapsedClass
        }
        list.setAttribute('class', classes)
        return list
    }
Create list element.
@param {Boolean} isCollapsed
@return {HTMLElement}