docs: function readApi(file, fn) {
    var ext = path.extname(file);
    if ('.js' === ext || '.ts' === ext) {
      readJsDoc(file, fn);
    } else if ('.yml' === ext) {
      readYml(file, fn);
    } else if ('.coffee' === ext) {
      readCoffee(file, fn);
    } else {
      throw new Error('Unsupported extension \'' + ext + '\'');
    }
  }