Why doesn't custom shortcut (to clear output in Jupyter Lab) work?

Question

Following the instruction to create custom shortcuts in Jupyter Lab, I've got the hide and show work but not the one to clear cell output (the first command entry). Does anyone know what the issue is? Thank you!

{
  "shortcuts": [
    {
      "command": "notebook:clear-cell-outputs",
      "keys": [
        "Ctrl L"
      ],
      "selector": ".jp-Notebook:focus"
    },  

    {
      "command": "notebook:hide-cell-outputs",
      "keys": [
        "O"
      ],
      "selector": ".jp-Notebook:focus"
    },  

    {
      "command": "notebook:show-cell-outputs",
      "keys": [
        "Shift O"
      ],
      "selector": ".jp-Notebook:focus"
    }
  ]
}

Answer 1

The correct command to use is notebook:clear-cell-output (no "s" at the end). The complete command list can be found here.