Count function counts documents in the database by query target is used only to get collection by tag so it'd be better to use nil ptr here.

DeleteArray removes documents list from a database by their ids.

DeleteOne removes a document from a database and then returns it into target.

LoadArray loads an array of documents from the database by query.

LoadOne function loads a first single target document by a query.

LoadStream function loads documents one by one into a target channel.

SaveOne saves a single source document to the database.

StreamLoader is a controller for a database cursor.