public final Flux<T> expandDeep(Function<? super T, ? extends Publisher<? extends T>> expander) {
		return expandDeep(expander, Queues.SMALL_BUFFER_SIZE);
	}
public final Flux<T> expandDeep(Function<? super T, ? extends Publisher<? extends T>> expander) {
		return expandDeep(expander, Queues.SMALL_BUFFER_SIZE);
	}
public final Flux < T > expandDeep ( Function < ? super T , ? extends Publisher < ? extends T > > expander ) { return expandDeep ( expander , Queues . SMALL_BUFFER_SIZE ) ; }
Recursively expand elements into a graph and emit all the resulting element,
in a depth-first traversal order.
<p>
That is: emit one value from this {@link Flux}, expand it and emit the first value
at this first level of recursion, and so on... When no more recursion is possible,
backtrack to the previous level and re-apply the strategy.
<p>
For example, given the hierarchical structure
<pre>
A
- AA
- aa1
B
- BB
- bb1
</pre>

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

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

@return a {@link Flux} expanded depth-first
Recursively expand elements into a graph and emit all the resulting element in a depth - first traversal order . <p > That is : emit one value from this { @link Flux } expand it and emit the first value at this first level of recursion and so on ... When no more recursion is possible backtrack to the previous level and re - apply the strategy . <p > For example given the hierarchical structure <pre > A - AA - aa1 B - BB - bb1 < / pre >