docs: def etag(etag):
      """Assumes the resource has the given etag and responds to If-None-Match and If-Match headers appropriately.
      ---
      tags:
        - Response inspection
      parameters:
        - in: header
          name: If-None-Match
        - in: header
          name: If-Match
      produces:
        - application/json
      responses:
        200:
          description: Normal response
        412:
          description: match
  
      """
      if_none_match = parse_multi_value_header(request.headers.get("If-None-Match"))
      if_match = parse_multi_value_header(request.headers.get("If-Match"))
  
      if if_none_match:
          if etag in if_none_match or "*" in if_none_match:
              response = status_code(304)
              response.headers["ETag"] = etag
              return response
      elif if_match:
          if etag not in if_match and "*" not in if_match:
              return status_code(412)
  
      # Special cases don't apply, return normal response
      response = view_get()
      response.headers["ETag"] = etag
      return response