anchor.diff:  mb_master_advertised_version() ->
       [3, 0, 0].
   
  -%% TODO: in 3.0 reimplement as compat_version 3.0 to make things
  -%% simpler.
   check_is_progress_tracking_supported() ->
  -    case rpc:multicall(ns_node_disco:nodes_wanted(), cluster_compat_mode, mb_master_advertised_version, [], 30000) of
  -        {Replies, []} ->
  -            [R || R <- Replies,
  -                  R < [2, 0, 2]] =:= [];
  +    case is_cluster_30() of
  +        true -> true;
           _ ->
  -            false
  +            case rpc:multicall(ns_node_disco:nodes_wanted(), cluster_compat_mode, mb_master_advertised_version, [], 30000) of
  +                {Replies, []} ->
  +                    [R || R <- Replies,
  +                          R < [2, 0, 2]] =:= [];
  +                _ ->
  +                    false
  +            end
       end.
   
   is_enabled_at(undefined = _ClusterVersion, _FeatureVersion) ->
  
positive.code: 
  is_enabled(FeatureVersion) ->
      is_enabled_at(get_compat_version(), FeatureVersion).
  
  is_index_aware_rebalance_on() ->
      Disabled = ns_config_ets_dup:unreliable_read_key(index_aware_rebalance_disabled, false),
  
negative.code:          check_is_progress_tracking_supported/0,
           get_replication_topology/0,
           is_node_compatible/2,
           split_live_nodes_by_version/1,
           is_cluster_30/0]).
  
  %% NOTE: this is rpc:call-ed by mb_master
  -export([supported_compat_version/0, mb_master_advertised_version/0]).
  