anchor.diff:  
     src = fetchgit ( removeAttrs (builtins.fromJSON ''{
     "url": "https://github.com/nvim-lua/plenary.nvim",
  -  "rev": "15c3cb9e6311dc1a875eacb9fc8df69ca48d7402",
  -  "date": "2021-08-19T19:04:12+02:00",
  -  "path": "/nix/store/fjj6gs1yc9gw3qh3xabf7mra4dlyac5a-plenary.nvim",
  -  "sha256": "0gdysws82vdcyfsfpkpg9wqw223vg6hh74pf821wxh8p6qg3r26m",
  +  "rev": "8c6cc07a68b65eb707be44598f0084647d495978",
  +  "date": "2021-09-26T16:13:25+02:00",
  +  "path": "/nix/store/j8hmr48blm4brq8rqv7b9m08vmalg8sp-plenary.nvim",
  +  "sha256": "05h5n7jj33y9vs6gc8hqlfd628j6i33s3c8fmfl6ahxwfygx2wpd",
  +  "fetchLFS": false,
     "fetchSubmodules": true,
     "deepClone": false,
     "leaveDotGit": false
  
positive.code:   "date": "2021-03-01T11:46:30-05:00",
    "path": "/nix/store/6dwfn64p3clcsxkq41b307q8izi0fvji-luaffifb",
    "sha256": "0nj76fw3yi57vfn35yvbdmpdbg9gmn5j1gw84ajs9w1j86sc0661",
    "fetchSubmodules": true,
    "deepClone": false,
    "leaveDotGit": false
  
negative.code:   "date": "2017-01-06T13:50:55+03:00",
    "path": "/nix/store/z72v77cw9188408ynsppwhlzii2dr740-lua-alt-getopt",
    "sha256": "1kq7r5668045diavsqd1j6i9hxdpsk99w8q4zr8cby9y3ws4q6rv",
    "fetchLFS": false,
    "fetchSubmodules": true,
    "deepClone": false,
    "leaveDotGit": false
  