code: function MarcIsoWriter(options) {
    if (!(this instanceof MarcIsoWriter)) {
      return new MarcIsoWriter(options);
    }
  
    // File with records in ISO2709 format.
    this.recordsFile = null;
    // Flag is true when write() can be performed.
    this.readyToWrite = false;
  
    // File options.
    options = options || {};
    this.options = {
      // Output data encoding.
      encoding: options.encoding || null
    }
  }
docs: /*
  The constructor of MARC ISO2709 writer.