code: function MempoolCache(options) {
    if (!(this instanceof MempoolCache))
      return new MempoolCache(options);
  
    this.logger = options.logger;
    this.chain = options.chain;
    this.network = options.network;
    this.db = null;
    this.batch = null;
  
    if (options.persistent)
      this.db = LDB(options);
  }
docs: Mempool Cache
  @ignore
  @constructor
  @param {Object} options