code: def add_instance_groups(self, jobflow_id, instance_groups):
          
          if type(instance_groups) != types.ListType:
              instance_groups = [instance_groups]
          params = {}
          params['JobFlowId'] = jobflow_id
          params.update(self._build_instance_group_list_args(instance_groups))
  
          return self.get_object('AddInstanceGroups', params,
                                 AddInstanceGroupsResponse, verb='POST')
docs: Adds instance groups to a running cluster.
  
          :type jobflow_id: str
          :param jobflow_id: The id of the jobflow which will take the
              new instance groups
              
          :type instance_groups: list(boto.emr.InstanceGroup)
          :param instance_groups: A list of instance groups to add to the job