how to get Key code from karabiner for Keyboard brightness working in kanata?

[niksingh710]

{
      "description": "Fn+, = keyboard backlight down, Fn+. = keyboard backlight up",
      "manipulators": [
        {
          "from": {
            "key_code": "comma",
            "modifiers": {
              "mandatory": [
                "fn"
              ]
            }
          },
          "to": [
            {
              "key_code": "illumination_decrement"
            }
          ],
          "type": "basic"
        },
        {
          "from": {
            "key_code": "period",
            "modifiers": {
              "mandatory": [
                "fn"
              ]
            }
          },
          "to": [
            {
              "key_code": "illumination_increment"
            }
          ],
          "type": "basic"
        },

^ above is the karabiner json config.

[Nxt3]

Also looking to figure this out.