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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 sign(self):
 """ Returns 1 if a credit should increase the value of the account, or -1 if a credit should decrease the value of the account. This is based on the account type as is standard accounting practice. The signs can be derrived from the following expanded form of the accounting equation: Assets = Liabilities + Equity + (Income - Expenses) Which can be rearranged as: 0 = Liabilities + Equity + Income - Expenses - Assets Further details here: https://en.wikipedia.org/wiki/Debits_and_credits """

        return -1 if self.type in (Account.TYPES.asset, Account.TYPES.expense) else 1