How to use the @ethersproject/bignumber.BigNumber.from function in @ethersproject/bignumber

chainId: 0
    };
    // Legacy unsigned transaction
    if (transaction.length === 6) {
        return tx;
    }
    try {
        tx.v = BigNumber.from(transaction[6]).toNumber();
    }
    catch (error) {
        console.log(error);
        return tx;
    }
    tx.r = hexZeroPad(transaction[7], 32);
    tx.s = hexZeroPad(transaction[8], 32);
    if (BigNumber.from(tx.r).isZero() && BigNumber.from(tx.s).isZero()) {
        // EIP-155 unsigned transaction
        tx.chainId = tx.v;
        tx.v = 0;
    }
    else {
        // Signed Tranasaction
        tx.chainId = Math.floor((tx.v - 35) / 2);
        if (tx.chainId < 0) {
            tx.chainId = 0;
        }
        let recoveryParam = tx.v - 27;
        const raw = transaction.slice(0, 6);
        if (tx.chainId !== 0) {
            raw.push(hexlify(tx.chainId));
            raw.push("0x");
            raw.push("0x");

}
    const tx = {
        nonce: handleNumber(transaction[0]).toNumber(),
        gasPrice: handleNumber(transaction[1]),
        gasLimit: handleNumber(transaction[2]),
        to: handleAddress(transaction[3]),
        value: handleNumber(transaction[4]),
        data: transaction[5],
        chainId: 0
    };
    // Legacy unsigned transaction
    if (transaction.length === 6) {
        return tx;
    }
    try {
        tx.v = BigNumber.from(transaction[6]).toNumber();
    }
    catch (error) {
        console.log(error);
        return tx;
    }
    tx.r = hexZeroPad(transaction[7], 32);
    tx.s = hexZeroPad(transaction[8], 32);
    if (BigNumber.from(tx.r).isZero() && BigNumber.from(tx.s).isZero()) {
        // EIP-155 unsigned transaction
        tx.chainId = tx.v;
        tx.v = 0;
    }
    else {
        // Signed Tranasaction
        tx.chainId = Math.floor((tx.v - 35) / 2);
        if (tx.chainId < 0) {

number(number) {
        return BigNumber.from(number).toNumber();
    }
    // Strict! Used on input.

// Data += ser_32(i)
        for (let i = 24; i >= 0; i -= 8) { data[33 + (i >> 3)] = ((index >> (24 - i)) & 0xff); }

        const I = arrayify(computeHmac(SupportedAlgorithms.sha512, this.chainCode, data));
        const IL = I.slice(0, 32);
        const IR = I.slice(32);

        // The private key
        let ki: string = null

        // The public key
        let Ki: string = null;

        if (this.privateKey) {
            ki = bytes32(BigNumber.from(IL).add(this.privateKey).mod(N));
        } else {
            const ek = new SigningKey(hexlify(IL));
            Ki = ek._addPoint(this.publicKey);
        }

        return new HDNode(_constructorGuard, ki, Ki, this.fingerprint, bytes32(IR), index, this.depth + 1, this.mnemonic, path);
    }

set value(value) {
        this.properties.value = BigNumber.from(value).toString();
    }

function handleNumber(value) {
    if (value === "0x") {
        return Zero;
    }
    return BigNumber.from(value);
}
const transactionFields = [

public set gas(gas) {
        if (gas) {
            this.properties.gas = BigNumber.from(gas).toString();
        }

        this.properties.gas = gas;
    }

const toUint = (val: PrimativeType, bytes: BytesNumber) =>
  hexZeroPad(BigNumber.from(val).toHexString(), bytes)