anchor.diff:  % Test cases
   -export([
       startup_speed/1,
  -    sync_speed/1
  +    sync_speed/1,
  +    stay_in_sync/1
   ]).
   
   -import(aest_nodes, [
  
positive.code:     Cfg = aest_nodes:ct_setup(InitCfg),
  
      Nodes = [n1, n2, n3],
      Height = proplists:get_value(height, Cfg),
      MineRate = proplists:get_value(mine_rate, Cfg),
      MineTimeout = proplists:get_value(mine_timeout, Cfg),
  
      setup_nodes(cluster(Nodes, #{mine_rate => MineRate}), Cfg),
      [start_node(N, Cfg) || N <- Nodes],
      wait_for_startup(Nodes, 0, Cfg),
      wait_for_value({height, Height}, Nodes, MineTimeout * Height, Cfg),
      Tag = io_lib:format("local-h~b", [Height]),
      Ref = aest_nodes:export(n1, Tag, Cfg),
      [kill_node(N, Cfg) || N <- Nodes],
      aest_nodes:ct_cleanup(Cfg),
      [{source, Ref}, {height, Height}, {mine_rate, MineRate}|Cfg].
  
  end_per_group(long_chain, _Cfg) -> ok.
  
  
negative.code: %=== TEST CASES ================================================================
  
  startup_speed(Cfg) ->
      Height = ?cfg(height),
  
      setup_nodes([spec(node, [], #{source => ?cfg(source)})], Cfg),
      start_node(node, Cfg),
      wait_for_startup([node], Height, Cfg),
      wait_for_value({height, Height}, [node], ?cfg(startup_timeout), Cfg).
  
  sync_speed(Cfg) ->
      [Height, MineRate] = ?cfg([height, mine_rate]),
  
      InitialNodes = [n1, n2, n3, n4],
  
      InitialNodeSpecs = cluster(InitialNodes, #{
          mine_rate => MineRate,
          source => ?cfg(source)
      }),
      NewNodesSpec = [
          spec(N, InitialNodes, #{mine_rate => MineRate})
  