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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_income_in_period(self, start: datetime, end: datetime) -> Decimal: """ Returns all income in the given period """

        accounts = self.get_income_accounts()
        income = Decimal(0)
        for acct in accounts:
            acc_agg = AccountAggregate(self.book, acct)
            acc_bal = acc_agg.get_balance_in_period(start, end)
            income += acc_bal

        return income