Описание тега concatmap
NoneConcat Map is a function from RxJava library, which returns a new Observable that emits items resulting from applying a function that you supply to each item emitted by the source Observable, where that function returns an Observable, and then emitting the items that result from concatinating those resulting Observables.
concatMap is a function from RxJava library, which returns a new Observable that emits items resulting from applying a function that you supply to each item emitted by the source Observable, where that function returns an Observable, and then emitting the items that result from concatinating those resulting Observables.