Hmm, try this:

``` py
def post(self):
    submit_checkbook = self.request.get('checkbook')
    submit_debit = self.request.get('debit')
    submit_credit = self.request.get('credit')

    user = users.get_current_user()

    if not user or not submit_checkbook:
        self.redirect('/userpage')
        return

    to_save = []

    checkbook = Checkbook()	
    checkbook.author = user
    checkbook.name = self.request.get('new_checkbook')
    checkbook.amount = float(self.request.get('amount', 0.0))
    checkbook.active = True
    to_save.append(checkbook)

    total_value = checkbook.amount

    transaction = Transaction()
    transaction.author = user

    if submit_debit:
        transaction.debit_amount = float(
            self.request.get('debit_amount', 0.0))
        transaction.description = self.request.get('debit_tran_des')
        transaction.credit_amount = 0.0
        transaction.total = total_value + transaction.debit_amount

        to_save.append(transaction)

    elif submit_credit:
        transaction.credit_amount = float(
            self.request.get('credit_amount', 0.0))
        transaction.description = self.request.get('credit_tran_des', 0.0)
        transaction.debit_amount = 0.0
        transaction.total = total_value - transaction.credit_amount

        to_save.append(transaction)

    total = Total()
    total.author = user
    total.checkbook_total = total_value
    to_save.append(total)

    db.put(to_save)

    self.redirect('/userpage')
```