static void assign(char_type& c1, char_type const& c2);
#include <sprout/string.hpp>
#include <sprout/assert.hpp>
using namespace sprout;
char x = 'H';
SPROUT_STATIC_CONSTEXPR char y = 'M';
int main() {
char_traits<char>::assign(x, y);
SPROUT_ASSERT_MSG(x == y, "y is assigned to x.");
}