function CSSSection(rng, source) {
						this.id = getId();
						/** @type {CSSSection} */
						this.parent = null;
						/** @type {CSSSection} */
						this.nextSibling = null;
						/** @type {CSSSection} */
						this.previousSibling = null;
						this._source = source;
						this._name = null;
						this._content = null;

						/**
						 * Custom data for current nodes, used by other modules for
						 * caching etc.
						 * @type {Object}
						 */
						this._data = {};

						if (!rng && source) {
							rng = range(0, source);
						}

						this.range = rng;
						this.children = [];
					}
Returns currect CSS source
@return {String}