shiftRight(numBits) {
    numBits &= 63;
    if (numBits == 0) {
      return this;
    } else {
      var high = this.high_;
      if (numBits < 32) {
        var low = this.low_;
        return Long.fromBits(
            (low >>> numBits) | (high << (32 - numBits)), high >> numBits);
      } else {
        return Long.fromBits(high >> (numBits - 32), high >= 0 ? 0 : -1);
      }
    }
  }
Returns this Long with bits shifted to the right by the given amount.
The new leading bits match the current sign bit.
@param {number} numBits The number of bits by which to shift.
@return {!Long} This shifted to the right by the given amount.