nat[3,3,3] matrix = [1, 1, 1, 
                     1, 1, 1, 
                     1, 1, 1, 
                     1, 1, 1, 
                     1, 0, 1, 
                     1, 1, 1, 
                     1, 1, 1, 
                     1, 1, 1, 
                     1, 1, 1];

nat xSize = 3;
nat ySize = 3;
nat zSize = 3;

bool found = false;
for (nat x = 0; x < xSize; x++) {
  for (nat y = 0; y < ySize; y++) {
    for (nat z = 0; z < zSize; z++) {
      if (matrix[x][y][z] == 0) {
        print("found: [");
        print(x as str);
        print(",");
        print(y as str);
        print(",");
        print(z as str);
        print("]\n");
        found = true;
        break;
      }
    }
    if (found) break;
  }
  if (found) break;
}