Suggestion: Better type for "once" method

[Tomucha]

Čusne?

First of all - amazing work, really. I wouldn't have the patience for this :-)

Suggestion: ref.once("...") takes String as an argument, which is not very "typed" and "Darty". So maybe this:

ref.once.value.then(...)
ref.once.childAdded.then(...)

...but it's probably to late for that, so maybe:

ref.once(EventType.value).then(...)
ref.once(EventType.childAdded).then(...)

... or at least list possible eventTypes in documentation of once method.

Or maybe it's all a moo point, and ref.onValue.first does exactly the same? In that case, it should also be mentioned in documentation, because it's not obvious (all that firebase magic, who knows what's going on behind the curtain).

[Janamou]

@Tomucha Good point! I will take a look at it.