+// New returns a new router (which implements the http.Handler
+// interface) that serves requests by calling Arvados API methods on
+// the given backend.
+//
+// If wrapCalls is not nil, it is called once for each API method, and
+// the returned method is used in its place. This can be used to
+// install hooks before and after each API call and alter responses;
+// see localdb.WrapCallsInTransaction for an example.
+func New(backend arvados.API, wrapCalls func(api.RoutableFunc) api.RoutableFunc) *router {