}

func typecheck(src string, conf *Config, info *Info) (*Package, error) {
	f := mustParse(src)
	if conf == nil {
		conf = &Config{
			Error:    func(err error) {}, // collect all errors
			Importer: defaultImporter(),
		}
	}
	return conf.Check(f.PkgName.Value, []*syntax.File{f}, info)
}

func mustTypecheck(src string, conf *Config, info *Info) *Package {
	pkg, err := typecheck(src, conf, info)
	if err != nil {