public class SomeUtility {
     public bool IsDoingSomething { get; private set; }

     public IEnumerator DoSomethingAsync() {
         IsDoingSomething = true;
         yield return new WaitForSeconds(2);
         IsDoingSomething = false;
     }
 }

while(!someUtilityInstance.IsDoingSomething)
     yield return null;

public static IEnumerator Await(this AsyncOperation operation) {
    while(!operation.isDone)
        yield return operation;
}

yield return SceneManager.LoadLevelAsync("blaaaah").Await();

yield return StartCoroutine(yourIEnumatorMethod());