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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 init(self, acct: Account, payer_acct: Account, gas_limit: int, gas_price: int) -> str: """ This interface is used to call the TotalSupply method in ope4 that initialize smart contract parameter. :param acct: an Account class that used to sign the transaction. :param payer_acct: an Account class that used to pay for the transaction. :param gas_limit: an int value that indicate the gas limit. :param gas_price: an int value that indicate the gas price. :return: the hexadecimal transaction hash value. """

        func = InvokeFunction('init')
        tx_hash = self.__sdk.get_network().send_neo_vm_transaction(self.__hex_contract_address, acct, payer_acct,
                                                                   gas_limit, gas_price, func)
        return tx_hash