anchor.diff:  
   default_admin_ctx(_) ->
       #{}.
  -
   
   
   %% @private
  
positive.code:     filter_params(expected_helper_args(HelperName), Params).
  
  
  prepare_user_ctx_params(HelperName, Params) ->
      filter_params(expected_user_ctx_params(HelperName), Params).
  
  
negative.code:     {ok, Scheme, str_utils:format_bin("~s:~B", [S3Host, S3Port])}.
  
  
  -spec strip_modifiers(Fields :: [field() | optional_field()]) -> [field()].
  strip_modifiers(Fields) ->
      lists:map(fun
          ({optional, Field}) -> Field;
  