Add history bloc

lib/bloc/history/bloc/history_bloc.dart

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+import 'dart:async';
+
+import 'package:bloc/bloc.dart';
+import 'package:meta/meta.dart';
+
+part 'history_event.dart';
+part 'history_state.dart';
+
+class HistoryBloc extends Bloc<HistoryEvent, HistoryState> {
+  HistoryBloc() : super(HistoryInitial());
+
+  @override
+  Stream<HistoryState> mapEventToState(
+    HistoryEvent event,
+  ) async* {
+    // TODO: implement mapEventToState
+  }
+}

lib/bloc/history/bloc/history_event.dart

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+part of 'history_bloc.dart';
+
+@immutable
+abstract class HistoryEvent {}

lib/bloc/history/bloc/history_state.dart

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+part of 'history_bloc.dart';
+
+@immutable
+abstract class HistoryState {}
+
+class HistoryInitial extends HistoryState {}