[IMPROVE] shortcuts for `then` inside `SomeViewModel`
[IMPROVE] shortcuts for `then` inside `SomeViewModel`

when call `then` rght after `when` - it's more likely that we are willing to skip `when` output rather than dispatcher proxy.

XCEssentials/UniFlow,maximkhatskevich/MKHUniFlow,maximkhatskevich/MKHUniFlow