anchor.diff:  %% statem helpers
   set_env_variable(Name, Value) ->
       EnvName = env_name(Name),
  -    true = os:putenv(EnvName, lists:flatten(io_lib:format("~p", [Value]))),
  +    StringValue=lists:flatten(io_lib:format("~p", [Value])),
  +    %% io:format("~s",[StringValue]),
  +    true = os:putenv(EnvName, StringValue),
       ok.
   
   set_app_env_variable(Name, Value) ->
  
positive.code: -compile(export_all).
  
  all() ->
      [config_prop_test].
  
  config_prop_test(_Config) ->
       ?assertEqual(true, proper:quickcheck(config_prop(), [long_result, 1000])).
  
  config_prop() ->
      ?FORALL(Cmds, proper_statem:commands(?MODULE),
  
negative.code: key() ->
      oneof([a, b, c, d, e, f, g]).
  
  real_any() ->
      %% ensure maps are tested!!!
      weighted_union([{1, map(any(), any())},
                      {10, any()}]).
  
  %% Abstract state machine
  initial_state() ->
      #{vars => [], envs => []}.
  
  command(_S) ->
      oneof([
                {call, ?MODULE, set_app_env_variable, [key(), real_any()]},
                {call, amoc_config_env, get, [key()]},
                {call, amoc_config_env, get, [key(), real_any()]},
                {call, ?MODULE, set_env_variable, [key(), real_any()]}
            ]).
  
  %%
  