def METHOD_NAME(
    items: typing.Iterable[CarrierT],
) -> typing.Tuple[int]:
    invalid_header_result = (trace.INVALID_TRACE_ID, trace.INVALID_SPAN_ID, 0)
    header = _extract_first_element(items)
    if header is None:
        return invalid_header_result
    fields = header.split(":")
    if len(fields) != 4:
        return invalid_header_result
    trace_id_str, span_id_str, _parent_id_str, flags_str = fields
    flags = _int_from_hex_str(flags_str, None)
    if flags is None:
        return invalid_header_result
    trace_id = _int_from_hex_str(trace_id_str, trace.INVALID_TRACE_ID)
    span_id = _int_from_hex_str(span_id_str, trace.INVALID_SPAN_ID)
    return trace_id, span_id, flags