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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 set_iam_policy( self, resource, policy, retry=google.api_core.gapic_v1.method.DEFAULT, timeout=google.api_core.gapic_v1.method.DEFAULT, metadata=None, ):
 """ Sets the access control policy on the specified resource. Replaces any existing policy. Example: Args: resource (str):
 REQUIRED: The resource for which the policy is being specified. ``resource`` is usually specified as a path. For example, a Project resource is specified as ``projects/{project}``. policy (Union[dict, ~google.cloud.iot_v1.types.Policy]):
 REQUIRED: The complete policy to be applied to the ``resource``. The size of the policy is limited to a few 10s of KB. An empty policy is a valid policy but certain Cloud Platform services (such as Projects) might reject them. If a dict is provided, it must be of the same form as the protobuf message :class:`~google.cloud.iot_v1.types.Policy` 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.iot_v1.types.Policy` 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 "set_iam_policy" not in self._inner_api_calls:
            self._inner_api_calls[
                "set_iam_policy"
            ] = google.api_core.gapic_v1.method.wrap_method(
                self.transport.set_iam_policy,
                default_retry=self._method_configs["SetIamPolicy"].retry,
                default_timeout=self._method_configs["SetIamPolicy"].timeout,
                client_info=self._client_info,
            )

        request = iam_policy_pb2.SetIamPolicyRequest(resource=resource, policy=policy)
        if metadata is None:
            metadata = []
        metadata = list(metadata)
        try:
            routing_header = [("resource", resource)]
        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["set_iam_policy"](
            request, retry=retry, timeout=timeout, metadata=metadata
        )