code: public final Flux<T> or(Publisher<? extends T> other) {
  		if (this instanceof FluxFirstEmitting) {
  			FluxFirstEmitting<T> publisherAmb = (FluxFirstEmitting<T>) this;
  
  			FluxFirstEmitting<T> result = publisherAmb.ambAdditionalSource(other);
  			if (result != null) {
  				return result;
  			}
  		}
  		return first(this, other);
  	}
docs: Pick the first {@link Publisher} between this {@link Flux} and another publisher
  to emit any signal (onNext/onError/onComplete) and replay all signals from that
  {@link Publisher}, effectively behaving like the fastest of these competing sources.
  
  <p>
  <img class="marble" src="doc-files/marbles/orForFlux.svg" alt="">
  
  @param other the {@link Publisher} to race with
  
  @return the fastest sequence
  @see #first