add flash with duration sample

.vscode/launch.json

@@ -0,0 +1,13 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Flutter",
+            "request": "launch",
+            "type": "dart"
+        }
+    ]
+}

example/ios/Flutter/Debug.xcconfig

@@ -1 +1,2 @@
+#include "Pods/Target Support Files/Pods-Runner/Pods-Runner.debug.xcconfig"
 #include "Generated.xcconfig"

example/ios/Flutter/Release.xcconfig

@@ -1 +1,2 @@
+#include "Pods/Target Support Files/Pods-Runner/Pods-Runner.release.xcconfig"
 #include "Generated.xcconfig"

example/lib/main.dart

@@ -37,7 +37,8 @@ class _MyAppState extends State<MyApp> {
             mainAxisAlignment: MainAxisAlignment.center,
               children: <Widget>[
             new Text('Device has flash: $_hasFlash\n Flash is on: $_isOn'),
-            new Slider(value: _intensity, onChanged: _isOn ? _intensityChanged : null)
+            new Slider(value: _intensity, onChanged: _isOn ? _intensityChanged : null),
+            new RaisedButton(onPressed: () async => await Lamp.flash(new Duration(seconds: 2)), child:  new Text("Flash for 2 seconds"))
           ]),
         ),
         floatingActionButton: new FloatingActionButton(

lib/lamp.dart

@@ -8,6 +8,6 @@ class Lamp {
   static Future turnOn({double intensity = 1.0}) => _channel.invokeMethod('turnOn', {'intensity' : intensity.clamp(0.01, 1.0)});
   static Future turnOff() => _channel.invokeMethod('turnOff');
   static Future<bool> get hasLamp async => await _channel.invokeMethod('hasLamp');
-  static Future flash(Duration duration) => turnOn().whenComplete(() => Future.delayed(duration, () => turnOff()));
+  static Future flash(Duration duration) => turnOn().whenComplete(() => new Future.delayed(duration, () => turnOff()));
 
 }