code: function encrypt(passwd) {
    let cipher = crypto.createCipher(algor, passwd),
      decryptedFileLocation = findFileLocation(DECRYPTED_FILENAME),
      decryptedFileFullPath = decryptedFileLocation + DECRYPTED_FILENAME,
      encryptedFileFullPath = decryptedFileLocation + ENCRYPTED_FILENAME, // we write encrypted file at same location as where we found decrypted file
      encBuff;
    if (!passwd) {
      throw new Error('encryption requires a password');
    }
    encBuff = Buffer.concat([cipher.update(readFile(decryptedFileFullPath)), cipher.final()]);
    writeFile(encryptedFileFullPath, encBuff);
    return md5FileSync(encryptedFileFullPath);
  }
docs: Write to disk encrypted file (.env.enc) from decrypted file (.env)
  @param     {String}    passwd      the key used to encrypt the .env into .env.enc
  @returns   {String}                writes the encrypted file to disk at same location where the encrypted file was found and returns its md5 checksum