add hidden option

input/option/option.go

@@ -15,6 +15,10 @@ func Default(in interface{}) variable.Option {
 	return variable.Default(value.New(in))
 }
 
+func Hidden(in *variable.Variable) {
+	variable.Hidden(in)
+}
+
 func Required(v *variable.Variable) {
 	variable.Required(v)
 }

input/variable/variable.go

@@ -40,6 +40,10 @@ func Required(v *Variable) {
 	v.Flag |= flag.Required
 }
 
+func Hidden(v *Variable) {
+	v.hidden = true
+}
+
 func WithParse(create Create, update Append) Option {
 	return func(v *Variable) {
 		v.append = func(Param) Append { return update }
@@ -99,6 +103,7 @@ type Variable struct {
 	Flag        flag.Flag
 	Type        ArgType
 	Default     value.Value
+	hidden      bool
 	Valid       []func(value.Value) error
 	params      Params
 	create      func(Param) Create
@@ -115,6 +120,10 @@ func (v Variable) Validate(in value.Value) error {
 	return nil
 }
 
+func (v Variable) IsHidden() bool {
+	return v.hidden
+}
+
 func (v Variable) IsArray() bool {
 	return v.Flag.IsArray()
 }