code: function ChainFlags(options) {
    if (!(this instanceof ChainFlags))
      return new ChainFlags(options);
  
    this.network = Network.primary;
    this.spv = false;
    this.witness = true;
    this.bip91 = false;
    this.bip148 = false;
    this.prune = false;
    this.indexTX = true;
    this.indexAddress = true;
  
    if (options)
      this.fromOptions(options);
  }
docs: Chain Flags
  @alias module:blockchain.ChainFlags
  @constructor