shortcuts.jupyterlab-settings

{
    "shortcuts": [
        {
            "command": "jupyterlab_code_formatter:format",
            "keys": [
                "Ctrl Shift F"
            ],
            "selector": ".jp-Notebook.jp-mod-editMode",
            "args": {}
        },
        {
            "command": "notebook:restart-run-all",
            "keys": [
                "N",
                "N"
            ],
            "selector": "[data-jp-kernel-user]:focus",
            "args": {}
        },
        {
            "command": "notebook:restart-clear-output",
            "keys": [
                "U",
                "U"
            ],
            "selector": "[data-jp-kernel-user]:focus",
            "args": {}
        }
    ]
}

Commenting/Uncommenting a block of code:

ctrl + }