code: function DupToPbn(opts) {
      if (!(this instanceof DupToPbn)) return new DupToPbn(opts);
  
      opts = opts || {};
      this.needDirectives = true;
      this.boardNumber = opts.boardNumber || 1;
  
      stream.Transform.call(this, opts);
  }
docs: Converts a DUP stream into PBN