code: def get_all_reserved_instances(self, reserved_instances_id=None,
                                     filters=None):
          
          params = {}
          if reserved_instances_id:
              self.build_list_params(params, reserved_instances_id,
                                     'ReservedInstancesId')
          if filters:
              self.build_filter_params(params, filters)
          return self.get_list('DescribeReservedInstances',
                               params, [('item', ReservedInstance)], verb='POST')
docs: Describes Reserved Instance offerings that are available for purchase.
  
          :type reserved_instance_ids: list
          :param reserved_instance_ids: A list of the reserved instance ids that
                                        will be returned. If not provided, all
                                        reserved instances will be returned.
  
          :type filters: dict
          :param filters: Optional filters that can be used to limit
                          the results returned.  Filters are provided
                          in the form of a dictionary consisting of
                          filter names as the key and filter values
                          as the value.  The set of allowable filter
                          names/values is dependent on the request
                          being performed.  Check the EC2 API guide
                          for details.
  
          :rtype: list
          :return: A list of :class:`boto.ec2.reservedinstance.ReservedInstance`