def make_transaction(self):
        """Create the transaction for this RecurredCost

        May only be used to create the RecurredCost's initial transaction.

        Returns:
            Transaction: The created transaction, also assigned to self.transaction. None if the amount is zero.
        """
        if self.pk:
            raise CannotRecreateTransactionOnRecurredCost(
                'The transaction for this recurred cost has already been created. You cannot create it again.'
            )

        amount = self.recurring_cost.get_amount(self.billing_cycle)

        # It is quite possible that there will be nothing to bill, in which
        # case we cannot create a transaction with no legs, nor can we create
        # legs with zero values. Therefore we don't create any transaction.
        if not amount:
            return None

        self.transaction = Transaction.objects.create(
            description='Created by recurring cost',
            date=self.billing_cycle.date_range.lower
        )

        # Use the SplitManager's custom queryset's split() method to get the
        # amount to be billed for each split
        splits = self.recurring_cost.splits.all().split(amount)

        # Create the transaction leg for the outbound funds
        # (normally to an expense account)
        self.transaction.legs.add(Leg.objects.create(
            transaction=self.transaction,
            amount=Money(amount, self.recurring_cost.currency),
            account=self.recurring_cost.to_account,
        ))

        for split, split_amount in splits:
            # Create the transaction legs for the inbound funds
            # (from housemate accounts)
            if split_amount:
                self.transaction.legs.add(Leg.objects.create(
                    transaction=self.transaction,
                    amount=Money(split_amount * -1, self.recurring_cost.currency),
                    account=split.from_account,
                ))

        return self.transaction
Create the transaction for this RecurredCost

        May only be used to create the RecurredCost's initial transaction.

        Returns:
            Transaction: The created transaction, also assigned to self.transaction. None if the amount is zero.