template<typename T, std::size_t N, typename Traits>
inline SPROUT_CONSTEXPR std::size_t
hash_value(sprout::basic_string<T, N, Traits> const& v);
#include <sprout/string.hpp>
using namespace sprout;
using type = string<8>;
SPROUT_STATIC_CONSTEXPR auto input = type("homuhomu");
SPROUT_STATIC_CONSTEXPR auto h = sprout::to_hash(input);
static_assert(h, "hash value generated from string.");