<commit_before>## Gone items

To represent content that is no longer available, the content-store will support items with a format
of "gone".  These will cause a gone route to be setup in the router so that the item returns a 410
HTTP status.

Items with a format of gone will have all routes setup in the same way as other item types (described in
route_registration.md), with the exception that instead of routing to the rendering_app, routes will be
created as gone routes.

For example, given an item including the following fields:

    {
      "base_path": "/gone-foo",
      "format": "gone",
      "routes": [<commit_msg>Include base path in routes, as mandated.<commit_after>## Gone items

To represent content that is no longer available, the content-store will support items with a format
of "gone".  These will cause a gone route to be setup in the router so that the item returns a 410
HTTP status.

Items with a format of gone will have all routes setup in the same way as other item types (described in
route_registration.md), with the exception that instead of routing to the rendering_app, routes will be
created as gone routes.

For example, given an item including the following fields:

    {
      "base_path": "/gone-foo",
      "format": "gone",
      "routes": [
        {"path": "/gone-foo", "type": "exact"},
{'fraction_non_alphanumeric': 0.0704647676161919, 'fraction_numerical': 0.004497751124437781, 'mean_word_length': 3.734042553191489, 'pattern_counts': {'":': 8, '<': 3, '<?xml version=': 0, '>': 3, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
{'dir': 'git-commits-cleaned', 'id': '7509681', 'n_tokens_mistral': 361, 'n_tokens_neox': 338, 'n_words': 200}