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Solve the following problem using Python, implementing the functions described below, one line at a time
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<USER_TASK:>
Description:
 def register(self, did, checksum, url, account, providers=None):
 """ Register or update a DID on the block chain using the DIDRegistry smart contract. :param did: DID to register/update, can be a 32 byte or hexstring :param checksum: hex str hash of TODO :param url: URL of the resolved DID :param account: instance of Account to use to register/update the DID :param providers: list of addresses of providers to be allowed to serve the asset and play a part in creating and fulfilling service agreements :return: Receipt """


        did_source_id = did_to_id_bytes(did)
        if not did_source_id:
            raise ValueError(f'{did} must be a valid DID to register')

        if not urlparse(url):
            raise ValueError(f'Invalid URL {url} to register for DID {did}')

        if checksum is None:
            checksum = Web3Provider.get_web3().toBytes(0)

        if not isinstance(checksum, bytes):
            raise ValueError(f'Invalid checksum value {checksum}, must be bytes or string')

        if account is None:
            raise ValueError('You must provide an account to use to register a DID')

        transaction = self._register_attribute(
            did_source_id, checksum, url, account, providers or []
        )
        receipt = self.get_tx_receipt(transaction)
        return receipt and receipt.status == 1