How to use the unchained-bitcoin.multisigPublicKeys function in unchained-bitcoin

function trezorInput(input, bip32Path) {
  const requiredSigners = multisigRequiredSigners(input.multisig);
  const addressType = multisigAddressType(input.multisig)
  const spendType = addressScriptTypes[addressType]
  return {
    script_type: spendType,
    multisig: {
      m: requiredSigners,
      pubkeys: multisigPublicKeys(input.multisig).map((publicKey) => trezorPublicKey(publicKey)),
      signatures: Array(requiredSigners).fill(''),
    },
    prev_hash: input.txid,
    prev_index: input.index,
    address_n: bip32PathToSequence(bip32Path),
    amount: input.amountSats.toString()
  };
}