Examine source code of Calculator

{
  "manifest_version": 3,
  "name": "Simple Calculator",
  "short_name": "Calculator",
  "version": "17",
  "version_name": "17 release",
  "description": "A simple and modern calculator add-on that remembers what you were just calculating.",
  "action": {
    "default_popup": "index.html?ver=15",
    "default_icon": "icon-192.png"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "calculator@lukadjo.t.me",
      "strict_min_version": "109.0"
    }
  },
  "commands": {
    "_execute_action": {
      "suggested_key": {
        "default": "Alt+Shift+C",
        "linux": "Alt+Shift+C",
        "windows": "Alt+Shift+C",
        "mac": "Alt+Shift+C"
      }
    }
  }
}