func NewBuilder(base Labels) *Builder {
	return &Builder{
		base: base,
		del:  make([]string, 0, 5),
		add:  make([]Label, 0, 5),
	}
}
func NewBuilder(base Labels) *Builder {
	return &Builder{
		base: base,
		del:  make([]string, 0, 5),
		add:  make([]Label, 0, 5),
	}
}
// NewBuilder returns a new LabelsBuilder