How to use the @bitgo/account-lib.Trx function in @bitgo/account-lib

signMessage(key: KeyPair, message: string | Buffer): Buffer {
    const toSign = this.toHexString(message);

    let prv = key.prv;
    if (this.isValidXprv(prv)) {
      prv = HDNode.fromBase58(prv)
        .getKey()
        .getPrivateKeyBuffer();
    }

    let sig = bitgoAccountLib.Trx.Utils.signString(toSign, prv, true);

    // remove the preceding 0x
    sig = sig.replace(/^0x/, '');

    return Buffer.from(sig, 'hex');
  }

compressedPubToHexAddress(pub: string): string {
    const byteArrayAddr = bitgoAccountLib.Trx.Utils.getByteArrayFromHexAddress(pub);
    const rawAddress = bitgoAccountLib.Trx.Utils.getRawAddressFromPubKey(byteArrayAddr);
    return bitgoAccountLib.Trx.Utils.getHexAddressFromByteArray(rawAddress);
  }