MergeLatest

MergeLatest joins elements from N input streams into stream of lists of size N. i-th element in list is the latest emitted element from i-th input stream. MergeLatest emits list for each element emitted from some input stream, but only after each stream emitted at least one element

'''Emits when''' element is available from some input and each input emits at least one element from stream start

'''Completes when''' all upstreams complete (eagerClose=false) or one upstream completes (eagerClose=true)

'''Cancels when''' downstream cancels