ASSERT_CONTAINER_SIZE( s, nSetSize );
for ( auto it = s.begin(); it != s.end(); ++it ) {
int key = it->key();
ASSERT_TRUE( s.erase_at( it ));
ASSERT_CONTAINER_SIZE( s, nSetSize );
for ( auto it = s.begin(); it != s.end(); ++it ) {
int key = it->key();
ASSERT_TRUE( s.erase_at( it ));