src/vs/editor/contrib/snippet/browser/snippetParser.ts/Transform/clone
class Transform:	clone(): Transform {
		let ret = new Transform();
		ret.regexp = new RegExp(this.regexp.source, '' + (this.regexp.ignoreCase ? 'i' : '') + (this.regexp.global ? 'g' : ''));
		ret._children = this.children.map(child => child.clone());
		return ret;
	}