anchor.diff:  %% Helpers
   %%--------------------------------------------------------------------
   
  -get_user_by_name(Name, Users) ->
  -    {Name, _} = proplists:lookup(Name, Users).
  -
   %% get_user_option is a wrapper on escalus_config:get_config/5,
   %% which can take either UserSpec (a proplist) or user name (atom)
   %% as the second argument
  
positive.code:          get_options/3,
           get_options/4,
           get_users/1,
           get_user_by_name/1,
           create_user/2,
           verify_creation/1,
           delete_user/2,
  
negative.code: -spec get_users(who()) -> [spec()].
  get_users(all) ->
      escalus_ct:get_config(escalus_users);
  get_users({by_name, _} = Names) ->
      All = get_users(all),
      get_users(Names, All);
  get_users(Users) ->
      Users.
  
  -spec get_users(who(), [spec()]) -> [spec()].
  get_users(all, Users) ->
      Users;
  get_users({by_name, Names}, Users) ->
      [get_user_by_name(Name, Users) || Name <- Names].
  
  -spec get_user_by_name(atom()) -> spec().
  get_user_by_name(Name) ->
      get_user_by_name(Name, get_users(all)).
  
  -spec get_user_by_name(atom(), [spec()]) -> [spec()].
  get_user_by_name(Name, Users) ->
      {Name, _} = proplists:lookup(Name, Users).
  
  
  create_user(Config, {_Name, UserSpec}) ->
      ClientProps = get_options(Config, UserSpec),
  