reactor-core/src/main/java/reactor/core/publisher/Flux.java
public final Flux<T> sampleFirst(Duration timespan) {
		return sampleFirst(t -> Mono.delay(timespan));
	}
public final Flux<T> sampleFirst(Duration timespan) {
		return sampleFirst(t -> Mono.delay(timespan));
	}
Repeatedly take a value from this {@link Flux} then skip the values that follow
within a given duration.

<p>
<img class="marble" src="doc-files/marbles/sampleFirstAtRegularInterval.svg" alt="">

@reactor.discard This operator discards elements that are not part of the sampling.

@param timespan the duration during which to skip values after each sample

@return a {@link Flux} sampled to the first item of each duration-based window