code: function PongPacket(nonce) {
    if (!(this instanceof PongPacket))
      return new PongPacket(nonce);
  
    Packet.call(this);
  
    this.nonce = nonce || encoding.ZERO_U64;
  }
docs: Represents a `pong` packet.
  @constructor
  @param {BN?} nonce
  @property {BN} nonce