Karabiner mod to sleep MacBook with external monitor

sleep.json

{
  "title": "Diego",
  "rules": [
    {
        "description": "Hold down left control to sleep",
        "manipulators": [
        {
          	"from": {
                "key_code": "left_control",
              	"modifiers": {
               		 "optional": [
                  		"caps_lock"
              ]
            }
          },
        	"parameters": {
                "basic.to_if_alone_timeout_milliseconds": 1900,
                "basic.to_if_held_down_threshold_milliseconds": 2000
              },
            "to_if_alone": [
                {
                  "key_code": "control"
                }
              ],
            "to_if_held_down": [
                {
                  "shell_command": "pmset sleepnow"
                }
              ],
          "type": "basic"
        }
      ]
    }
  ]
}