code: def parse_connection_option(
      header: str, pos: int, header_name: str
  ) -> Tuple[ConnectionOption, int]:
      
      item, pos = parse_token(header, pos, header_name)
      return cast(ConnectionOption, item), pos
docs: Parse a Connection option from ``header`` at the given position.
  
      Return the protocol value and the new position.
  
      Raise :exc:`~websockets.exceptions.InvalidHeaderFormat` on invalid inputs.