code: def get_deployment_group(self, project, deployment_group_id, action_filter=None, expand=None):
          
          route_values = {}
          if project is not None:
              route_values['project'] = self._serialize.url('project', project, 'str')
          if deployment_group_id is not None:
              route_values['deploymentGroupId'] = self._serialize.url('deployment_group_id', deployment_group_id, 'int')
          query_parameters = {}
          if action_filter is not None:
              query_parameters['actionFilter'] = self._serialize.query('action_filter', action_filter, 'str')
          if expand is not None:
              query_parameters['$expand'] = self._serialize.query('expand', expand, 'str')
          response = self._send(http_method='GET',
                                location_id='083c4d89-ab35-45af-aa11-7cf66895c53e',
                                version='5.0-preview.1',
                                route_values=route_values,
                                query_parameters=query_parameters)
          return self._deserialize('DeploymentGroup', response)
docs: GetDeploymentGroup.
          [Preview API] Get a deployment group by its ID.
          :param str project: Project ID or project name
          :param int deployment_group_id: ID of the deployment group.
          :param str action_filter: Get the deployment group only if this action can be performed on it.
          :param str expand: Include these additional details in the returned object.
          :rtype: :class:`<DeploymentGroup> <azure.devops.v5_0.task_agent.models.DeploymentGroup>`