Data - struct for restore/backup mem_storage.

MemData - struct for mem_storage.

Request - postShorten handler request.

Response - postShorten handler response.

ShortenBatchRequest - batch handler request.

ShortenBatchResponse - batch handler response.

ShortURL - struct.

Stats - struct for stats.

StatsResponse - get /api/internal/stats handlers response.

URL - struct original_url and deleted flag.

UserURLsResponse - get /api/user/urls handler request.

DeleteBatchRequest - delete handler request.