anchor.diff:  next_state(S,_R,{call, _, local_compare1, []}) ->
       S.
   
  -
  -%% Property wrapped with sometimes to copy with
  -%% some non-determinism in tests - assuming it comes
  -%% from eleveldb as all hashtree operations are thought
  -%% to be deterministic.
  -%% JDM: This should no longer be needed w/ final updates from MvM, no?
  -sometimes_correct() ->
  -    sometimes_correct(3).
  -
  -sometimes_correct(N) ->
  -    ?SOMETIMES(N, prop_correct()).
   
   %% Property to generate a series of commands against the
   %% hashtrees and afterwards force them to a comparable state.
  
positive.code: %% The command frequencies are deliberately manipulated to make it more
  %% likely that compares will take place once both trees are updated.
  %%
  
  
  %% Notes/Questions for JDM
  %% There's much knowledge in here about how *_index_hashtrees work, which makes
  %% me worried that hashtree itself isn't factored correctly. Example: why would it be
  %% different if memory levels are used or not? Why _should_ hashtree allow it to be?
  
  
  -module(hashtree_eqc).
  
negative.code:         %% Update snapshots/trees. If memory is enabled must test with update_tree
          %% If not, can use the method used by kv/yz_index_hashtree and separate
          %% the two steps, dumping the result from update_perform.
          [{SnapshotWeight, {call, ?MODULE, update_tree, [t1, s1]}}     || Snap1 == undefined] ++
          [{SnapshotWeight, {call, ?MODULE, update_snapshot, [t1, s1]}} || Snap1 == undefined, MemLevels == 0] ++
          [{SnapshotWeight, {call, ?MODULE, update_perform, [t1]}}      || Snap1 == created, MemLevels == 0] ++
  