beets/.github/flake8-problem-matcher.json

{
    "problemMatcher": [
        {
            "owner": "flake8",
            "pattern": [
                {
                    "regexp": "^(.*?):(\\d+):(\\d+): (.*)$",
                    "file": 1,
                    "line": 2,
                    "column": 3,
                    "message": 4
                }
            ]
        }
    ]
}