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