How to use the assetgraph.Asset function in assetgraph

function checkCompatibility(asset, Class) {
  if (typeof Class === 'undefined') {
    Class = AssetGraph.Asset;
  } else if (typeof Class === 'string') {
    Class = AssetGraph[Class];
  }
  return (
    asset instanceof Class ||
    !asset._type ||
    Class.prototype instanceof AssetGraph[asset._type] ||
    !!(asset.isImage && Class === AssetGraph.Image) || // Svg is modelled as a subclass of Xml, not Image
    !!(asset.isImage && Class === AssetGraph.Font) // Svg can be used as a font as well
  );
}

key =>
      AssetGraph[key] &&
      AssetGraph[key].prototype &&
      AssetGraph[key].prototype.findOutgoingRelationsInParseTree ===
        AssetGraph.Asset.prototype.findOutgoingRelationsInParseTree
  );