anchor.diff:  
   -spec init_per_round(atom(), [binary()]) -> ok.
   init_per_round(Fun, Keys) when Fun =:= append;
  -                               Fun =:= get ->
  +                               Fun =:= get;
  +                               Fun =:= getbit;
  +                               Fun =:= getrange ->
     [{ok, Deleted} | OkKeys] =
       edis_db:run(
         edis_db:process(0),
  
positive.code: -export([all/0,
           init/0, init_per_testcase/1, init_per_round/2,
           quit/0, quit_per_testcase/1, quit_per_round/2]).
  -export([append/1, decr/1, decrby/1, get/1]).
  
  %% ====================================================================
  %% External functions
  
negative.code:     edis_db:process(0),
      #edis_command{cmd = <<"GET">>, args = [<<"test-string">>],
                    group = strings, result_type = bulk}).
  
  -spec getbit([binary()]) -> 1 | 0.
  getbit(Keys) ->
    edis_db:run(
      edis_db:process(0),
      #edis_command{cmd = <<"GETBIT">>, args = [<<"test-string">>,
                                                random:uniform(length(Keys)) - 1],
                    group = strings, result_type = number}).
  
  -spec getrange([binary()]) -> binary().
  getrange(_) ->
    edis_db:run(
      edis_db:process(0),
      #edis_command{cmd = <<"GETRANGE">>, args = [<<"test-string">>, 1, -2],
                    group = strings, result_type = number}).
  