// isBCP47LanguageTag is the validation function for validating if the current field's value is a valid BCP 47 language tag, as parsed by language.Parse
funcisBCP47LanguageTag(flFieldLevel)bool{
field:=fl.Field()
iffield.Kind()==reflect.String{
_,err:=language.Parse(field.String())
returnerr==nil
}
panic(fmt.Sprintf("Bad field type %T",field.Interface()))