Temporarily include nucleus in the project

app/src/main/java/nucleus/presenter/delivery/DeliverFirst.java

@@ -0,0 +1,38 @@
+package nucleus.presenter.delivery;
+
+import rx.Notification;
+import rx.Observable;
+import rx.functions.Func1;
+
+public class DeliverFirst<View, T> implements Observable.Transformer<T, Delivery<View, T>> {
+
+    private final Observable<View> view;
+
+    public DeliverFirst(Observable<View> view) {
+        this.view = view;
+    }
+
+    @Override
+    public Observable<Delivery<View, T>> call(Observable<T> observable) {
+        return observable.materialize()
+            .take(1)
+            .switchMap(new Func1<Notification<T>, Observable<? extends Delivery<View, T>>>() {
+                @Override
+                public Observable<? extends Delivery<View, T>> call(final Notification<T> notification) {
+                    return view.map(new Func1<View, Delivery<View, T>>() {
+                        @Override
+                        public Delivery<View, T> call(View view) {
+                            return view == null ? null : new Delivery<>(view, notification);
+                        }
+                    });
+                }
+            })
+            .filter(new Func1<Delivery<View, T>, Boolean>() {
+                @Override
+                public Boolean call(Delivery<View, T> delivery) {
+                    return delivery != null;
+                }
+            })
+            .take(1);
+    }
+}