render = function(expression, baseNode, options) {
	    utils.clearNode(baseNode);

	    var settings = new Settings(options);

	    var tree = parseTree(expression, settings);
	    var node = buildTree(tree, expression, settings).toNode();

	    baseNode.appendChild(node);
	}
Sometimes we want to pull out the innermost element of a group. In most
cases, this will just be the group itself, but when ordgroups and colors have
a single element, we want to pull that out.