static SPROUT_CONSTEXPR bool lt(char_type c1, char_type c2) SPROUT_NOEXCEPT;
#include <sprout/string.hpp>
using namespace sprout;
SPROUT_STATIC_CONSTEXPR char x = 'H';
SPROUT_STATIC_CONSTEXPR char y = 'M';
SPROUT_STATIC_CONSTEXPR auto result = char_traits<char>::lt(x, y);
static_assert(result, "x is less than y.");