anchor.diff:           get_options/3,
            get_options/4,
            get_users/1,
  +         get_users/2,
            get_user_by_name/1,
  +         get_user_by_name/2,
            create_user/2,
            verify_creation/1,
            delete_user/2,
  
positive.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_user_by_name(Name, All) || Name <- Names];
  get_users(Users) ->
      Users.
  
  get_user_by_name(Name) ->
      get_user_by_name(Name, get_users(all)).
  
  create_user(Config, {_Name, UserSpec}) ->
      ClientProps = get_options(Config, UserSpec),
  
negative.code: %% Helpers
  %%--------------------------------------------------------------------
  
  %% 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
  