How to show broadcast (simultaneous sending of two messages) in sequence diagrams in PlantUml

Question

I have this bit of plantuml:

@startuml

title Sequence diagram

A -> B : First
B -> C : Second
B -> A : Third

@enduml

It renders like this:

I would like to get this instead, with two arrows "happening concurrently":

Any hints on how to achieve this are appreciated!

Answer 1

You might find an answer with the Teoz pragma https://plantuml.com/teoz

@startuml
!pragma teoz true
title Sequence diagram

A -> B : First
B -> C : Second
&B -> A : Third

@enduml