let currentFile = 0;
let filePath = `./bip39-${timestamp}-${currentFile}.txt`;

entropy.on('nextFile', function () {
    writeStream.end();

    ++currentFile;
    filePath = `./bip39-${timestamp}-${currentFile}.txt`;;
    writeStream = fs.createWriteStream(filePath);
});

let writeStream = fs.createWriteStream(filePath);

while (true) {
    const mnemonic = bip39.entropyToMnemonic(entropy.next()) + '\r\n';
    writeStream.write(mnemonic);
}