Header file visitor.hpp
#define SIPLASPLAS_VARIANT_VISITOR_HPP
#include <siplasplas/utility/function.hpp>
namespace cpp
{
namespace {}
template <typename R>
struct VariantVisitorTraits;
template <typename R, typename F, typename = void>
struct VariantVisitor;
template <typename R, typename F>
struct VariantVisitor<R, F, void_t<typename F::ResultType>;
template <typename R, typename ... Fs>
VariantVisitor<R, Function<std::decay_t<Fs>...>> visitor(Fs&&... fs);
}