utils/event_emitter library

1. rx_mvvm package
2. documentation
3. utils/event_emitter.dart

rx_mvvm package

1. Libraries
2. command_events
3. infra/injector
4. infra/view
5. infra/view_model
6. infra/view_model_provider
7. rx_mvvm
8. utils/event_emitter
9. utils/listener_sink