write(path, options) {
        // Throw an error if this method is called on a non file field
        if (this.file === undefined)
            throw new Error(
                'HyperExpress.Request.MultipartField.write(path, options) -> This method can only be called on a field that is a file type.'
            );

        // Return a promise which resolves once write stream has finished
        const reference = this;
        return new Promise((resolve, reject) => {
            const writable = FileSystem.createWriteStream(path, options);
            writable.on('close', resolve);
            writable.on('error', reject);
            reference.file.stream.pipe(writable);
        });
    }
Saves this multipart file content to the specified path.
Note! You must specify the file name and extension in the path itself.

@param {String} path Path with file name to which you would like to save this file.
@param {stream.WritableOptions} options Writable stream options
@returns {Promise}