text: from pathlib import PurePath
  import re
  
  from werkzeug.routing import BaseConverter, ValidationError
  
  
  def rewrite_supplier_asset_path(url, assets_url):
      """
      Supplier frontend has an authenticated endpoint for declaration documents: frameworks.download_declaration_document
  
      Sometimes other apps need to be able to show declaration documents to users who are not the supplier who uploaded
      the document. This function allows them to convert the supplier frontend URL into an assets URL.
  
      You must ensure that you are only exposing this document to authorised users.
      """
      parts = url.split('/suppliers/assets')
      if len(parts) == 2:
          return assets_url + parts[1]
      return url
  
  
  class SafePurePathConverter(BaseConverter):
      """
          Like the default :class:`PathConverter`, but it converts
          the output to a :class:`pathlib.PurePath` and ensures it
          contains no path components consisting only of dots.
      """
  
      regex = "[^/].*?"
      weight = 200
  
      _disallowed_path_part_re = re.compile(r"\.+$")
  
      def to_python(self, value):
          pth = PurePath(value)
          if not pth.parts:
              raise ValidationError("All path parts squashed out")
  
          for part in pth.parts:
              if self._disallowed_path_part_re.match(part):
                  raise ValidationError(f"Disallowed path part {part!r}")
  
          return pth
  