code: function hotpOptions(options = {}) {
    return Object.assign(
      {
        algorithm: 'sha1',
        createHmacSecret: hotpSecret,
        crypto: null,
        digits: 6,
        encoding: 'ascii'
      },
      options
    );
  }
docs: Generates options for HOTP
  
  @module otplib-core/hotpOptions
  @param {number} options.digits - the output token length
  @param {string} options.encoding - the encoding of secret
  @return {object}