-spec delete_storage(cowboy_req:req()) -> {json, map()} | {status, integer()}.

-spec get_save(cowboy_req:req()) -> {json, map()} | {status, integer()}.

-spec get_storage(cowboy_req:req()) -> {json, map()} | {status, integer()}.

-spec list_saves(cowboy_req:req()) -> {json, map()}.

-spec list_storage(cowboy_req:req()) -> {json, map()}.

-spec put_save(cowboy_req:req()) -> {json, map()} | {json, integer(), map(), map()}.

-spec put_storage(cowboy_req:req()) ->
                     {json, map()} | {json, integer(), map(), map()} | {status, integer()}.