Function stringify

src/Serializer.js:25–35

(element, index, children, callback)

 * @return {string}
 */
export function stringify (element, index, children, callback) {
	switch (element.type) {
		case LAYER: if (element.children.length) break
		case IMPORT: case NAMESPACE: case DECLARATION: return element.return = element.return || element.value
		case COMMENT: return ''
		case KEYFRAMES: return element.return = element.value + '{' + serialize(element.children, callback) + '}'
		case RULESET: if (!strlen(element.value = element.props.join(','))) return ''
	}

	return strlen(children = serialize(element.children, callback)) ? element.return = element.value + '{' + children + '}' : ''
}