SyncFirebase.kt

override fun all(): Future<List<Either<NetError, Task>>> = Future(async(CommonPool) {
    val snapshot: DataSnapshot = suspendCoroutine { cont: Continuation<DataSnapshot> ->
        taskReference.addValueEventListener(object : ValueEventListener {
            override fun onCancelled(error: DatabaseError) {
                cont.resumeWithException(IOException("Error retrieving data"))
            }
             override fun onDataChange(dataSnapshot: DataSnapshot) {
                cont.resume(dataSnapshot)
            }
        })
    }
    listOf(Either.Left(NetError.Unknown))
})