Examine source code of Image Sequence Sidebar

{
  "manifest_version": 2,
  "name": "Image Sequence Sidebar",
  "version": "1.0",
  "description": "Adds a sidebar that displays similarly numbered images on a webpage",
  "icons": {
    "128": "file-image-o.png"
  },
  "sidebar_action": {
    "default_title": "Images",
    "default_panel": "sidebar.html",
    "default_icon": "file-image-o.png"
  },
  "permissions": [
    "tabs"
  ],
  "commands": {
    "_execute_sidebar_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+I"
      }
    }
  }
}