How to use the @ethersproject/strings.toUtf8Bytes function in @ethersproject/strings

const encseed = looseArrayify(searchPath(data, "encseed"));
    if (!encseed || (encseed.length % 16) !== 0) {
        logger.throwArgumentError("invalid encseed", "json", json);
    }
    const key = arrayify(pbkdf2(password, password, 2000, 32, "sha256")).slice(0, 16);
    const iv = encseed.slice(0, 16);
    const encryptedSeed = encseed.slice(16);
    // Decrypt the seed
    const aesCbc = new aes.ModeOfOperation.cbc(key, iv);
    const seed = aes.padding.pkcs7.strip(arrayify(aesCbc.decrypt(encryptedSeed)));
    // This wallet format is weird... Convert the binary encoded hex to a string.
    let seedHex = "";
    for (let i = 0; i < seed.length; i++) {
        seedHex += String.fromCharCode(seed[i]);
    }
    const seedHexBytes = toUtf8Bytes(seedHex);
    const privateKey = keccak256(seedHexBytes);
    return new CrowdsaleAccount({
        _isCrowdsaleAccount: true,
        address: ethaddr,
        privateKey: privateKey
    });
}

signMessage(message) {
        let data = ((typeof (message) === "string") ? toUtf8Bytes(message) : message);
        return this.getAddress().then((address) => {
            // https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_sign
            return this.provider.send("eth_sign", [address.toLowerCase(), hexlify(data)]);
        });
    }
    unlock(password) {

import { pbkdf2 } from "@ethersproject/pbkdf2";
import { defineReadOnly } from "@ethersproject/properties";
import { SigningKey } from "@ethersproject/signing-key";
import { computeHmac, ripemd160, sha256, SupportedAlgorithms } from "@ethersproject/sha2";
import { computeAddress } from "@ethersproject/transactions";
import { Wordlist, wordlists } from "@ethersproject/wordlists";

import { Logger } from "@ethersproject/logger";
import { version } from "./_version";
const logger = new Logger(version);

const N = BigNumber.from("0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141");


// "Bitcoin seed"
const MasterSecret = toUtf8Bytes("Bitcoin seed");

const HardenedBit = 0x80000000;

// Returns a byte with the MSB bits set
function getUpperMask(bits: number): number {
   return ((1 << bits) - 1) << (8 - bits);
}

// Returns a byte with the LSB bits set
function getLowerMask(bits: number): number {
   return (1 << bits) - 1;
}

function bytes32(value: BigNumber | Uint8Array): string {
    return hexZeroPad(hexlify(value), 32);
}

function expand(word) {
    const output = [];
    Array.prototype.forEach.call(toUtf8Bytes(word), (c) => {
        // Acute accent
        if (c === 47) {
            output.push(204);
            output.push(129);
            // Grave accent
        }
        else if (c === 45) {
            output.push(204);
            output.push(128);
        }
        else {
            output.push(c);
        }
    });
    return toUtf8String(output);
}

if (connection.headers) {
            for (const key in connection.headers) {
                headers[key.toLowerCase()] = { key: key, value: String(connection.headers[key]) };
                if (["if-none-match", "if-modified-since"].indexOf(key.toLowerCase()) >= 0) {
                    allow304 = true;
                }
            }
        }
        if (connection.user != null && connection.password != null) {
            if (url.substring(0, 6) !== "https:" && connection.allowInsecureAuthentication !== true) {
                logger.throwError("basic authentication requires a secure https url", Logger.errors.INVALID_ARGUMENT, { argument: "url", url: url, user: connection.user, password: "[REDACTED]" });
            }
            const authorization = connection.user + ":" + connection.password;
            headers["authorization"] = {
                key: "Authorization",
                value: "Basic " + base64Encode(toUtf8Bytes(authorization))
            };
        }
    }
    if (json) {
        options.method = "POST";
        options.body = json;
        headers["content-type"] = { key: "Content-Type", value: "application/json" };
    }
    const flatHeaders = {};
    Object.keys(headers).forEach((key) => {
        const header = headers[key];
        flatHeaders[header.key] = header.value;
    });
    options.headers = flatHeaders;
    const runningTimeout = (function () {
        let timer = null;

function hashMessage(message) {
    if (typeof (message) === "string") {
        message = strings_1.toUtf8Bytes(message);
    }
    return keccak256_1.keccak256(bytes_1.concat([
        strings_1.toUtf8Bytes(exports.messagePrefix),
        strings_1.toUtf8Bytes(String(message.length)),
        message
    ]));
}
exports.hashMessage = hashMessage;

export function hashMessage(message: Bytes | string): string {
    if (typeof(message) === "string") { message = toUtf8Bytes(message); }
    return keccak256(concat([
        toUtf8Bytes(messagePrefix),
        toUtf8Bytes(String(message.length)),
        message
    ]));
}

function _pack(type, value, isArray) {
    switch (type) {
        case "address":
            if (isArray) {
                return bytes_1.zeroPad(value, 32);
            }
            return bytes_1.arrayify(value);
        case "string":
            return strings_1.toUtf8Bytes(value);
        case "bytes":
            return bytes_1.arrayify(value);
        case "bool":
            value = (value ? "0x01" : "0x00");
            if (isArray) {
                return bytes_1.zeroPad(value, 32);
            }
            return bytes_1.arrayify(value);
    }
    var match = type.match(regexNumber);
    if (match) {
        //let signed = (match[1] === "int")
        var size = parseInt(match[2] || "256");
        if ((size % 8 != 0) || size === 0 || size > 256) {
            throw new Error("invalid number type - " + type);
        }