public final Flux<T> expand(Function<? super T, ? extends Publisher<? extends T>> expander) {
		return expand(expander, Queues.SMALL_BUFFER_SIZE);
	}
public final Flux<T> expand(Function<? super T, ? extends Publisher<? extends T>> expander) {
		return expand(expander, Queues.SMALL_BUFFER_SIZE);
	}
public final Flux < T > expand ( Function < ? super T , ? extends Publisher < ? extends T > > expander ) { return expand ( expander , Queues . SMALL_BUFFER_SIZE ) ; }
Recursively expand elements into a graph and emit all the resulting element using
a breadth-first traversal strategy.
<p>
That is: emit the values from this {@link Flux} first, then expand each at a first level of
recursion and emit all of the resulting values, then expand all of these at a second
level and so on..
<p>
For example, given the hierarchical structure
<pre>
A
- AA
- aa1
B
- BB
- bb1
</pre>

Expands {@code Flux.just(A, B)} into
<pre>
A
B
AA
BB
aa1
bb1
</pre>

@param expander the {@link Function} applied at each level of recursion to expand
values into a {@link Publisher}, producing a graph.

@return an breadth-first expanded {@link Flux}
Recursively expand elements into a graph and emit all the resulting element using a breadth - first traversal strategy . <p > That is : emit the values from this { @link Flux } first then expand each at a first level of recursion and emit all of the resulting values then expand all of these at a second level and so on .. <p > For example given the hierarchical structure <pre > A - AA - aa1 B - BB - bb1 < / pre >