<@U0JMFMS7N>: This seems to work: ``` fun add...

# announcements

[andrewoma]

@florian: This seems to work:

fun addOneTimeListener(onLoaded: (T) -> Unit) {
        addOnChangedListener(object : (T) -> Unit {
            override fun invoke(t: T) {
                onLoaded(t)
                removeOnChangedListener(this)
            }
        })
    }