func set(items []string) map[string]bool {
	s := make(map[string]bool)
	for _, v := range items {
		s[v] = true
	}
	return s
}

var spaceParensRx = regexp.MustCompile(` \(\S+?\)`)

func featureWithoutContext(f string) string {
	if !strings.Contains(f, "(") {
		return f
	}
	return spaceParensRx.ReplaceAllString(f, "")
}

// portRemoved reports whether the given port-specific API feature is