ReadonlymatchHow pattern should be matched against the incoming command.
ReadonlypatternLiteral pattern (e.g. '/scan' or 'receipt_acc:').
Optional ReadonlyparseOptional payload extractor. Returns '' when no payload is present.
ReadonlyhandleHandler invoked when this route matches.
Declarative route entry — a tuple of (pattern, matcher, parser, handler).
argis always a string: empty string ('') means "no argument supplied". Likewiseparsereturns '' to indicate "no payload after the prefix".