for example if you have switchMap, then right side...

# rx

[ursus]

for example if you have switchMap, then right side is subscribed after left side emits, but what if that was already subscribed before rotation,. After rotation to have it subscribed you need left side to emit, which would most likely caused work on the right side, and emitting an item, which is almost never what you want. Especially if you already had that emit, and you just want to reemit the cached value to the ui, etc.