docs: def base64_64format_decode(s: str) -> Optional[bytes]:
      """
      Reverse :func:`base64_64format_encode`.
  
      Original purpose and notes:
  
      - THIS IS ANOTHER WAY OF DOING BLOBS: base64 encoding, e.g. a string like
        ``64'cGxlYXN1cmUu'`` is a base-64-encoded BLOB (the ``64'...'`` bit is my
        representation).
      - regex from http://stackoverflow.com/questions/475074
      - better one from http://www.perlmonks.org/?node_id=775820
  
      """
      if len(s) < 4 or not s.startswith("64'") or not s.endswith("'"):
          return None
      return base64.b64decode(s[3:-1])