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