func (s Schema) assertKeyType(name string, code Type) {
	key := s.mustGetKey(name)
	if key.Type != code {
		panic(fmt.Sprintf("key '%s' has type code %d, not %d", name, key.Type, code))
	}
}
func (s Schema) assertKeyType(name string, code Type) {
	key := s.mustGetKey(name)
	if key.Type != code {
		panic(fmt.Sprintf("key '%s' has type code %d, not %d", name, key.Type, code))
	}
}
// Assert that the Key with the given name as the given type. Panic if no Key
// with such name exists, or if it does not match the tiven type.