code: public static <T> Flux<T> merge(Publisher<? extends Publisher<? extends T>> source) {
  		return merge(source,
  				Queues.SMALL_BUFFER_SIZE,
  				Queues.XS_BUFFER_SIZE);
  	}
docs: Merge data from {@link Publisher} sequences emitted by the passed {@link Publisher}
  into an interleaved merged sequence. Unlike {@link #concat(Publisher) concat}, inner
  sources are subscribed to eagerly.
  <p>
  <img class="marble" src="doc-files/marbles/mergeAsyncSources.svg" alt="">
  
  <p>
  Note that merge is tailored to work with asynchronous sources or finite sources. When dealing with
  an infinite source that doesn't already publish on a dedicated Scheduler, you must isolate that source
  in its own Scheduler, as merge would otherwise attempt to drain it before subscribing to
  another source.
  
  @param source a {@link Publisher} of {@link Publisher} sources to merge
  @param <T> the merged type
  
  @return a merged {@link Flux}