split method Null safety

Link split(
  1. bool test(
    1. Request request
    ),
  2. Link left,
  3. [Link right = const PassthroughLink()]
)

Split requests after this link

Implementation

Link split(
  bool Function(Request request) test,
  Link left, [
  Link right = const PassthroughLink(),
]) =>
    concat(
      _RouterLink(
        (Request request) => test(request) ? left : right,
      ),
    );