k
let s = lvl[sofs_h..sofs_h + height as usize].iter().fold(
String::with_capacity((height + 10) * (width + 10)),
|ss, row| {
row[sofs_w..sofs_w + width as usize]
.iter()
.fold(ss, |sss, &block_idx| sss + blocks[block_idx])
+ "\n"
},
);
print!("{}", s);