with_spanmacro attaches it back at the end so any call to this GenServer with sub part containing a
with_spanwill get the last set context as a parent
detachbut it doesn't really have an effect on the outcome so I keep forgetting to fix that
I had to do:
current_ctx = Ctx.attach(ctx) ... Span.end_span(child) Ctx.detach(current_ctx)
In a similar example with a
GenServer.call/3instead of a Task.
That's why I had to do this in the manually set span example