code: function range(a, b) {
      if (b === undefined) {
          b = a;
          a = 0;
      }
      b = Math.max(b, 0);
      var arr = [];
      for (var i = a; i < b; i++) {
          arr.push(i);
      }
      return new ndarray_1.NDArray(arr, { datatype: 'i32' });
  }
docs: Generate array of integers within given range.
  If both a and b are specified then return [a,b)
  if only a is specifed then return [0,a)