if v.kind() != Map {
		v.panicNotMap()
	}
	return &MapIter{m: v}
}

// Force slow panicking path not inlined, so it won't add to the
// inlining budget of the caller.
// TODO: undo when the inliner is no longer bottom-up only.
//
//go:noinline
func (f flag) panicNotMap() {
	f.mustBe(Map)
}