How to use the @polkadot/util-crypto.mnemonicToMiniSecret function in @polkadot/util-crypto

: _suri;
    const { password, phrase, path } = keyExtractSuri(suri);
    let seed;

    if (isHex(phrase, 256)) {
      seed = hexToU8a(phrase);
    } else {
      const str = phrase as string;
      const parts = str.split(' ');

      if ([12, 15, 18, 21, 24].includes(parts.length)) {
        // FIXME This keeps compat with older versions, but breaks compat with subkey
        // seed = type === 'sr25519'
        //   ? mnemonicToMiniSecret(phrase, password)
        //   : mnemonicToSeed(phrase, password);
        seed = mnemonicToMiniSecret(phrase, password);
      } else {
        assert(str.length <= 32, 'specified phrase is not a valid mnemonic and is invalid as a raw seed at > 32 bytes');

        seed = stringToU8a(str.padEnd(32));
      }
    }

    const keypair = type === 'sr25519'
      ? schnorrkelFromSeed(seed)
      : naclFromSeed(seed);
    const derived = keyFromPath(keypair, path, type);

    return createPair(type, derived, meta, null);
  }

ctx.onmessage = async ({ data: { pairType } }): Promise => {
  await cryptoWaitReady();

  const seed = mnemonicGenerate();
  const miniSecret = mnemonicToMiniSecret(seed);
  const { publicKey } = pairType === 'sr25519'
    ? schnorrkelKeypairFromSeed(miniSecret)
    : naclKeypairFromSeed(miniSecret);

  ctx.postMessage({
    publicKey,
    seed
  });
};

export default function generator (test: string[][], options: GeneratorOptions): GeneratorMatch {
  const mnemonic = options.withHex
    ? undefined
    : mnemonicGenerate(12);
  const seed = mnemonic
    ? mnemonicToMiniSecret(mnemonic)
    : randomAsU8a();
  const pair = options.type === 'sr25519'
    ? schnorrkelKeypairFromSeed(seed)
    : naclKeypairFromSeed(seed);
  const address = encodeAddress(pair.publicKey);
  const { count, offset } = calculate(test, address, options);

  return {
    address,
    count,
    mnemonic,
    offset,
    seed
  };
}