if (B_t const * const hej = dynamic_cast<B_t *>(du)) {
B_t const*const hej=dynamic_cast  < B_t* >(du)) {
const B_t *const hej=dynamic_cast<B_t*>
MN:B_t *const hej=dynamic_cast<B_t*>
MN::B_t *const hej=dynamic_cast<MN::B_t*>
 B_t const * const hej=dynamic_cast<B_t const*>
B_t const * const hej=dynamic_cast<B_t const*>
