Asynchronously grabs proxy URL's.
Source
Future fetch() async { var client = new http.Client(); for (String url in urls) { var file = new File(url), proxyStream = new ProxyStream(); if (await file.exists()) { await for (ProxyDef proxyDef in file.openRead().transform(proxyStream)) { _stream.add(proxyDef); } } else { var response = await client.get(url); var _ctrl = new StreamController<List<int>>(); _ctrl ..add(response.bodyBytes) ..close(); await _stream.addStream(_ctrl.stream.transform(proxyStream)); } } _stream.close(); client.close(); }