constructor(taglib, dependencyChain) {
    ok(
      dependencyChain instanceof DependencyChain,
      '"dependencyChain" is not valid',
    );

    this.dependencyChain = dependencyChain;

    this.taglib = taglib;
    this.filePath = taglib.filePath;
    this.dirname = taglib.dirname;
  }
We load a taglib definion using this class. Properties in the taglib
definition (which is just a JavaScript object with properties)
are mapped to handler methods in an instance of this type.


@param {Taglib} taglib The initially empty Taglib instance that we will populate
@param {String} path The file system path to the taglib that we are loading