title: What are use cases for coroutines?
body: <p>The concept of a <a href="http://en.wikipedia.org/wiki/Coroutine" rel="noreferrer">coroutine</a> sounds very interesting, but I don't know, if it makes sense in a real productive environment? What are use cases for coroutines, where the coroutine implementation is more elegant, simpler or more efficient than other methods?</p>