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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_total_supply(self) -> int: """ This interface is used to call the TotalSupply method in ope4 that return the total supply of the oep4 token. :return: the total supply of the oep4 token. """

        func = InvokeFunction('totalSupply')
        response = self.__sdk.get_network().send_neo_vm_transaction_pre_exec(self.__hex_contract_address, None, func)
        try:
            total_supply = ContractDataParser.to_int(response['Result'])
        except SDKException:
            total_supply = 0
        return total_supply