docs: def dump_options_header(header, options):
      """The reverse function to :func:`parse_options_header`.
  
      :param header: the header to dump
      :param options: a dict of options to append.
      """
      segments = []
      if header is not None:
          segments.append(header)
      for key, value in iteritems(options):
          if value is None:
              segments.append(key)
          else:
              segments.append("%s=%s" % (key, quote_header_value(value)))
      return "; ".join(segments)