code: public Observable<Boolean> deleteConversations(List<ChatConversationBase> conversationsToDelete) {
          return asObservable(new Executor<Boolean>() {
              @Override
              void execute(ChatStore store, Emitter<Boolean> emitter) {
                  store.beginTransaction();
                  boolean isSuccess = true;
                  for (int i = 0; i < conversationsToDelete.size(); i++) {
                      isSuccess = isSuccess && store.deleteConversation(conversationsToDelete.get(i).getConversationId());
                  }
                  store.endTransaction();
                  emitter.onNext(isSuccess);
                  emitter.onCompleted();
              }
          });
      }
docs: Delete conversations from the store.
  
  @param conversationsToDelete List of conversations to delete.
  @return Observable emitting result.