RxJava Android scheduler

AndroidScheduler.java

package rx.concurrency;

import android.os.Handler;
import android.os.Looper;
import rx.Scheduler;
import rx.Subscription;
import rx.concurrency.ExecutorScheduler;
import rx.util.AtomicObservableSubscription;
import rx.util.functions.Func2;

import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;

/**
 * Executes work on the Android UI thread.
 * This scheduler should only be used to update the ui.
 */
public class AndroidScheduler extends Scheduler {

    private static final AndroidScheduler INSTANCE = new AndroidScheduler();

    public static AndroidScheduler getInstance() {
        return INSTANCE;
    }

    private AndroidScheduler() {
    }

    @Override
    public <T> Subscription schedule(final T state, final Func2<Scheduler, T, Subscription> action) {
        final AtomicObservableSubscription subscription = new AtomicObservableSubscription();
        final Scheduler _scheduler = this;

        Handler handler = new Handler(Looper.getMainLooper());

        handler.post(new Runnable() {
            @Override
            public void run() {
                subscription.wrap(action.call(_scheduler, state));
            }
        });

        return subscription;
    }

    @Override
    public <T> Subscription schedule(T t, Func2<Scheduler, T, Subscription> schedulerTSubscriptionFunc2, long l, TimeUnit timeUnit) {
        return null;
    }


}