code: function bnpDLShiftTo(n, r) {
    var i;
    for (i = this.t - 1; i >= 0; --i)
      r[i + n] = this[i];
    for (i = n - 1; i >= 0; --i)
      r[i] = 0;
    r.t = this.t + n;
    r.s = this.s;
  }
docs: (protected) r = this << n*DB