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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 GetStandardAddress(self):
 """ Get the Wallet's default address. Raises: Exception: if no default contract address is set. Returns: UInt160: script hash. """

        for contract in self._contracts.values():
            if contract.IsStandard:
                return contract.ScriptHash

        raise Exception("Could not find a standard contract address")