code: function TXRecord(tx, block) {
    if (!(this instanceof TXRecord))
      return new TXRecord(tx, block);
  
    this.tx = null;
    this.hash = null;
    this.mtime = util.now();
    this.height = -1;
    this.block = null;
    this.index = -1;
    this.time = 0;
  
    if (tx)
      this.fromTX(tx, block);
  }
docs: TXRecord
  @constructor
  @param {TX} tx
  @param {BlockMeta?} block