func RegisterFeature(key string) {
	if _, ok := featureMap[key]; !ok {
		maxFeature++
		featureMap[key] = maxFeature
	}
}
RegisterFeature register a feature
package generator
type feature int
const (
	placeHolder feature = iota
)
var (
	featureMap = make(map[string]feature)
	maxFeature = placeHolder
)
func HasFeature(list []feature, key string) bool {
	target, ok := getFeature(key)
	if !ok {
		return false
	}
	for _, f := range list {
		if f == target {
			return true
		}
	}
	return false
}