use static_visitor as a base class for all visitors
use static_visitor as a base class for all visitors

tempbottle/variant,tangrams/variant,edwiincao/variant,daniel-j-h/variant,daniel-j-h/variant,tangrams/variant,tempbottle/variant,tempbottle/variant,tangrams/variant,daniel-j-h/variant,edwiincao/variant,edwiincao/variant