I was about to disagree with you, that we use "when" when several things might be true, but then I realised that in those cases each of the possibilities will happen, but at different times, like "when the light is read you stop, when it is green you go".

It's fascinating how many quite subtle rules you internalise about your native language without realising it.

Developers will stop arguing about arbitrary syntactical nuances when pigs fly!

  when light_is_green {
     go
  } when light_is_red {
     stop
  } otherwise {
     go_very_fast
  }