// return a reference to a DOM element by ID
function e(id) {
	return document.getElementById(id);
}

// return or set the display property of a DOM element by ID or reference
function d(element, display) {
	if (typeof element == 'string') element = e(element);
	if (typeof element != 'object') return false;
	if (arguments.length == 2) element.style.display = display ? '' : 'none';
	return (element.style.display == 'none' ? false : true);
}

// toggle display of a DOM element by ID or reference
function toggle(element) {
	d(element, !d(element));
}