def update(<EOL>self, scope, event_subscription_name, event_subscription_update_parameters, custom_headers=None, raw=False, polling=True, **operation_config):
raw_result = self._update_initial(<EOL>scope=scope,<EOL>event_subscription_name=event_subscription_name,<EOL>event_subscription_update_parameters=event_subscription_update_parameters,<EOL>custom_headers=custom_headers,<EOL>raw=True,<EOL>**operation_config<EOL>)<EOL>def get_long_running_output(response):<EOL><INDENT>deserialized = self._deserialize('<STR_LIT>', response)<EOL>if raw:<EOL><INDENT>client_raw_response = ClientRawResponse(deserialized, response)<EOL>return client_raw_response<EOL><DEDENT>return deserialized<EOL><DEDENT>lro_delay = operation_config.get(<EOL>'<STR_LIT>',<EOL>self.config.long_running_operation_timeout)<EOL>if polling is True: polling_method = ARMPolling(lro_delay, **operation_config)<EOL>elif polling is False: polling_method = NoPolling()<EOL>else: polling_method = polling<EOL>return LROPoller(self._client, raw_result, get_long_running_output, polling_method)<EOL>
Update an event subscription.

        Asynchronously updates an existing event subscription.

        :param scope: The scope of existing event subscription. The scope can
         be a subscription, or a resource group, or a top level resource
         belonging to a resource provider namespace, or an EventGrid topic. For
         example, use '/subscriptions/{subscriptionId}/' for a subscription,
         '/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}'
         for a resource group, and
         '/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/{resourceProviderNamespace}/{resourceType}/{resourceName}'
         for a resource, and
         '/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.EventGrid/topics/{topicName}'
         for an EventGrid topic.
        :type scope: str
        :param event_subscription_name: Name of the event subscription to be
         updated
        :type event_subscription_name: str
        :param event_subscription_update_parameters: Updated event
         subscription information
        :type event_subscription_update_parameters:
         ~azure.mgmt.eventgrid.models.EventSubscriptionUpdateParameters
        :param dict custom_headers: headers that will be added to the request
        :param bool raw: The poller return type is ClientRawResponse, the
         direct response alongside the deserialized response
        :param polling: True for ARMPolling, False for no polling, or a
         polling object for personal polling strategy
        :return: An instance of LROPoller that returns EventSubscription or
         ClientRawResponse<EventSubscription> if raw==True
        :rtype:
         ~msrestazure.azure_operation.AzureOperationPoller[~azure.mgmt.eventgrid.models.EventSubscription]
         or
         ~msrestazure.azure_operation.AzureOperationPoller[~msrest.pipeline.ClientRawResponse[~azure.mgmt.eventgrid.models.EventSubscription]]
        :raises: :class:`CloudError<msrestazure.azure_exceptions.CloudError>`