BlocProvider=> bloc parameter

안녕하세요 강사님, 강사님의 강의와 동일하게 코딩을 했는데요,,

BlocProvider 안에 'bloc' 이라는 parameter가 정의 되어있지 않다고 나오는데요 어떤 오류인지 잘 모르겠습니다.

                    ---------------Error ----------------

Compiler message:

lib/main.dart:15:7: Error: No named parameter with the name 'bloc'.

      bloc: _cartBloc,

      ^^^^

file:///Users/jeongjaegyu/Downloads/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_bloc-0.19.0/lib/src/bloc_provider.dart:20:3: Context: Found this candidate, but the arguments don't match.

  BlocProvider({

  ^

lib/catalog.dart:30:9: Error: No named parameter with the name 'bloc'.

        bloc: _cartBloc,

        ^^^^

file:///Users/jeongjaegyu/Downloads/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_bloc-0.19.0/lib/src/bloc_provider.dart:20:3: Context: Found this candidate, but the arguments don't match.

  BlocProvider({

  ^

링크를 따라 들어가면 

BlocProvider({
  Key key,
  @required ValueBuilder<T> builder,
  Widget child,
}) : super(
        key: key,
        builder: builder,
        dispose: (_, bloc) => bloc?.dispose(),
        child: child,
      );

이부분을 표시해주는데요

어디를 확인하는 것이 좋을까요?

builder: (BuildContext context) => _cartBloc