How to use the @iota/transaction.value function in @iota/transaction

if (!isMultipleOfTransactionLength(offset)) {
        throw new RangeError(errors.ILLEGAL_TRANSACTION_OFFSET)
    }

    if (!Number.isInteger(length)) {
        throw new TypeError(errors.ILLEGAL_BUNDLE_LENGTH)
    }

    if (!isMultipleOfTransactionLength(length)) {
        throw new RangeError(errors.ILLEGAL_BUNDLE_LENGTH)
    }

    let sum = 0

    for (let bundleOffset = 0; bundleOffset < length; bundleOffset += TRANSACTION_LENGTH) {
        sum += tritsToValue(transactionValue(buffer, offset + bundleOffset))
    }

    return sum
}