DataURL represents data related to a URL.

DataURLite represents a simplified version of data related to a URL.

DataUser represents data related to a user.

DeleteURL represents a request to delete one or more URLs associated with a user.

Request describes the user's request.

RequestUser describes the user's request for user-related operations.

Response describes the server's response.

ResponseUser describes the server's response for user-related operations.

StatsResponse describes the response with urls and users counts.

Key is an alias for string and represents a key used in various contexts.