**Techniques adopted: ** Mvvm + Clean Architecture Dagger2 kotlin

**Code explain ** Code structure: Clean Architecture: 3 modules: data, domain, presentation

Presentation Module:
MVVM pattern:
M: data+domain layer
   ui/model: define the data UI needed
             eg: add another data item predictedLeftTime in TramItemViewData.kt, to show tram will arrive "in * minutes"
   ui/mapper is the place convert data to UI needed.
             eg:  data format conversion is done in TramItemViewDataMapper.kt

VM: ui/viewmodel,
    ->TramViewModel: make api call, and update livedata

V: ui/Activity, Fragment, and xml
    ->react use action(press refresh button) and delege to TramViewModel
    ->observe livedata in TramViewModel
    ->update UI passively


Dagger2:
di/module: provide Repository, ViewModel, others classes that constructor have @inject annotation
di/component: delcare injection places:  fragment and others