code: async function(path) {
        return fs.writeFileAsync(path, JSON.stringify(this.__cache, null, 2), "UTF-8")
          .catch(e => console.error(`Error exporting cache to ${path}:` + e.message));
      }
docs: Exports the cache to an external file. Note that the structure of the cache
  data can change any time. Do not build anything on it. You have been warned.
  @param path {String}
  @return {void}