char * err = "Too much wrapping in mv_yx_in_dir_legal().";
exit_err( INT8_MIN == wrap_west_east || INT8_MIN == wrap_north_south
|| INT8_MAX == wrap_west_east || INT8_MAX == wrap_north_south, err);
char * err = "Too much wrapping in mv_yx_in_dir_legal().";
exit_err( INT8_MIN == wrap_west_east || INT8_MIN == wrap_north_south
|| INT8_MAX == wrap_west_east || INT8_MAX == wrap_north_south, err);