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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_blob( self, name, payload, delegates=None, retry=google.api_core.gapic_v1.method.DEFAULT, timeout=google.api_core.gapic_v1.method.DEFAULT, metadata=None, ):
 """ Signs a blob using a service account's system-managed private key. Example: Args: name (str):
 The resource name of the service account for which the credentials are requested, in the following format: ``projects/-/serviceAccounts/{ACCOUNT_EMAIL_OR_UNIQUEID}``. payload (bytes):
 The bytes to sign. delegates (list[str]):
 The sequence of service accounts in a delegation chain. Each service account must be granted the ``roles/iam.serviceAccountTokenCreator`` role on its next service account in the chain. The last service account in the chain must be granted the ``roles/iam.serviceAccountTokenCreator`` role on the service account that is specified in the ``name`` field of the request. The delegates must have the following format: ``projects/-/serviceAccounts/{ACCOUNT_EMAIL_OR_UNIQUEID}`` retry (Optional[google.api_core.retry.Retry]):
 A retry object used to retry requests. If ``None`` is specified, requests will not be retried. timeout (Optional[float]):
 The amount of time, in seconds, to wait for the request to complete. Note that if ``retry`` is specified, the timeout applies to each individual attempt. metadata (Optional[Sequence[Tuple[str, str]]]):
 Additional metadata that is provided to the method. Returns: A :class:`~google.cloud.iam_credentials_v1.types.SignBlobResponse` instance. Raises: google.api_core.exceptions.GoogleAPICallError: If the request failed for any reason. google.api_core.exceptions.RetryError: If the request failed due to a retryable error and retry attempts failed. ValueError: If the parameters are invalid. """

        # Wrap the transport method to add retry and timeout logic.
        if "sign_blob" not in self._inner_api_calls:
            self._inner_api_calls[
                "sign_blob"
            ] = google.api_core.gapic_v1.method.wrap_method(
                self.transport.sign_blob,
                default_retry=self._method_configs["SignBlob"].retry,
                default_timeout=self._method_configs["SignBlob"].timeout,
                client_info=self._client_info,
            )

        request = common_pb2.SignBlobRequest(
            name=name, payload=payload, delegates=delegates
        )
        if metadata is None:
            metadata = []
        metadata = list(metadata)
        try:
            routing_header = [("name", name)]
        except AttributeError:
            pass
        else:
            routing_metadata = google.api_core.gapic_v1.routing_header.to_grpc_metadata(
                routing_header
            )
            metadata.append(routing_metadata)

        return self._inner_api_calls["sign_blob"](
            request, retry=retry, timeout=timeout, metadata=metadata
        )