What is "kelluke"

Kelluke ("Little bell", originally named after a Campanula) is a clear and lemon-flavoured non-alcoholic soft drink produced since 1965 by A. Le Coq (formerly and colloquially known as Tartu Õlletehas (Tartu Brewery)) in Estonia. After a temporary name change since 2001, Kelluke made its comeback in 2006. Since 2010 Kelluke has been produced without preservatives. It has been compared to Sprite, but the original makers of the drink were not familiar with Sprite before the recipe for Kelluke was finished.