book_for_for_in_while.js

compute_sum: if (matrix) {
 for(var x = 0; x < matrix.length; x++) {
   var row = matrix[x];
   if (!row) break compute_sum;
   for(var y = 0; y < row.length; y++) {
     var cell = row[y];
     if (isNaN(cell)) break compute_sum;
     sum += cell;
   }
 }
 success = true;
}