anchor.diff:      L1 = lists:map(fun({Pos, Sz}) -> Pos + Sz end, L0),
       lists:last(lists:sort(L1)).
   
  --define(TESTDIR, "./eqc").
  -
   cleanup() ->
       [begin
            Fs = filelib:wildcard(?TESTDIR ++ Glob),
  
positive.code: 
  get_written_interval(L) ->
      ?LET({O, Ln}, elements(L), {O+1, Ln-1}).
   
  %% INITIALIZATION
  
  -record(state, {pid, prev_extra = 0,
                  planned_writes=[],
                  planned_trims=[],
                  written=[],
                  trimmed=[]}).
  
  initial_state() -> #state{written=[{0,1024}]}.
  initial_state(I, T) -> #state{written=[{0,1024}],
                                planned_writes=I,
                                planned_trims=T}.
  
  weight(_S, rewrite) -> 1;
  weight(_S, _) -> 2.
  
negative.code:       (Pos < Offset + Len andalso Offset + Len < Pos + Sz) ->
      get_overlaps(Offset, Len, T, [Ck|Acc0]);
  get_overlaps(Offset, Len, [_Ck|T], Acc0) ->
      get_overlaps(Offset, Len, T, Acc0).
  
  %% Inefficient but simple easy code to verify by eyes - returns all
  