exit_err(0 == file, world, err_open);
if ( write_uint32_bigendian(world->seed, file)
|| write_uint32_bigendian(world->turn, file)
exit_err(0 == file, world, err_open);
if ( write_uint32_bigendian(world->seed, file)
|| write_uint32_bigendian(world->turn, file)