이 노트를 로드하는 중에 오류가 발생했습니다. 파일에 액세스할 수 있는지 확인한 후 다시 시도하세요.

GitHub에서 이 노트북을 볼 권한이 있는지 확인하고 Colab이 GitHub API를 사용하도록 승인하세요.

https://github.com/flutter/codelabs/blob/master/tfrs-flutter/step1/backend/retrieval/retrieval.ipynb 
Fetch for https://api.github.com/repos/flutter/codelabs/contents/tfrs-flutter/step1/backend/retrieval?per_page=100&ref=master failed: {"message":"No commit found for the ref master","documentation_url":"https://docs.github.com/v3/repos/contents/","status":"404"}
CustomError: Fetch for https://api.github.com/repos/flutter/codelabs/contents/tfrs-flutter/step1/backend/retrieval?per_page=100&ref=master failed: {"message":"No commit found for the ref master","documentation_url":"https://docs.github.com/v3/repos/contents/","status":"404"}
    at new jN (https://ssl.gstatic.com/colaboratory-static/common/629c0c0894a411e1c2ceca4f346d8829/external_binary_l10n__ko.js:2479:68)
    at wa.program_ (https://ssl.gstatic.com/colaboratory-static/common/629c0c0894a411e1c2ceca4f346d8829/external_binary_l10n__ko.js:2462:436)
    at za (https://ssl.gstatic.com/colaboratory-static/common/629c0c0894a411e1c2ceca4f346d8829/external_binary_l10n__ko.js:16:57)
    at wa.next_ (https://ssl.gstatic.com/colaboratory-static/common/629c0c0894a411e1c2ceca4f346d8829/external_binary_l10n__ko.js:14:195)
    at kaa.next (https://ssl.gstatic.com/colaboratory-static/common/629c0c0894a411e1c2ceca4f346d8829/external_binary_l10n__ko.js:17:48)
    at b (https://ssl.gstatic.com/colaboratory-static/common/629c0c0894a411e1c2ceca4f346d8829/external_binary_l10n__ko.js:17:309)
 GitHub 승인 요청