static fromFileAsync(path, opts) {
        if (process.browser) throw new Error("Workbook.fromFileAsync is not supported in the browser");
        return new externals.Promise((resolve, reject) => {
            fs.readFile(path, (err, data) => {
                if (err) return reject(err);
                resolve(data);
            });
        }).then(data => Workbook.fromDataAsync(data, opts));
    }
Loads a workbook from file.
@param {string} path - The path to the workbook.
@param {{}} [opts] - Options
@returns {Promise.<Workbook>} The workbook.
@ignore