end abstract method
void
end()
Suppresses the linter error must_use_outcome. Returns void in every
subtype — calling .end() is the "I am intentionally discarding this
Outcome" marker, so the call site never needs to think about a Future.
For Async this means the underlying future is detached internally via
unawaited(...); if you actually need to await completion, use .value.
Implementation
void end();