How to use the @zilliqa-js/util.validation.isBase58 function in @zilliqa-js/util

*/
    [
      'amount',
      'toAddr'
    ].forEach(key => {
      if (!payload.hasOwnProperty(key)) {
        throw new Error(
          errorsCode.WrongRequiredparam + key
        );
      }
    });

    const storage = new BrowserStorage();
    let forConfirm = await storage.get(fields.CONFIRM_TX);

    if (validation.isBase58(payload.toAddr)) {
      payload.toAddr = decodeBase58(payload.toAddr);
    } else if (validation.isBech32(payload.toAddr)) {
      payload.toAddr = fromBech32Address(payload.toAddr);
    }

    payload.toAddr = toChecksumAddress(payload.toAddr);

    try {
      forConfirm = forConfirm[fields.CONFIRM_TX];
      forConfirm.push(payload);
    } catch(err) {
      forConfirm = [payload];
    }

    await storage.set(new BuildObject(fields.CONFIRM_TX, forConfirm));
    this.notificationsCounter(forConfirm);

private getAddressType() {
    const addrBool = validation.isAddress(this.raw);
    const base58Bool = validation.isBase58(this.raw);
    const bech32Bool = validation.isBech32(this.raw);
    const bech32TestNetBool = validation.isBech32TestNet(this.raw);
    const checksumBool = isValidChecksumAddress(this.raw);

    if (addrBool === true && checksumBool === false) {
      this.addressType = AddressType.bytes20;
      this.bytes20 = this.raw.startsWith('0x')
        ? this.raw.substring(2)
        : this.raw;
      return;
    }

    if (addrBool === true && checksumBool === true) {
      this.addressType = AddressType.checkSum;
      this.bytes20 = this.raw.toLowerCase().substring(2);
      return;