code: function GetBlocksPacket(locator, stop) {
    if (!(this instanceof GetBlocksPacket))
      return new GetBlocksPacket(locator, stop);
  
    Packet.call(this);
  
    this.version = common.PROTOCOL_VERSION;
    this.locator = locator || [];
    this.stop = stop || null;
  }
docs: Represents a `getblocks` packet.
  @constructor
  @param {Hash[]} locator
  @param {Hash?} stop
  @property {Hash[]} locator
  @property {Hash|null} stop