Nunu Ult Reactivation

Just a small suggestion.

If Nunu were released today (besides having a knockup) his ult would work as "Channels for 3 seconds. Activate again to end early." or similarly to the sion Q, "Hold R to channel for up to 3 seconds.". As it is, the ult feels... wrong. Mechanically, it works sort of like the Xerath ult - moving interrupts. And that isn't a bad thing, but allowing reactivating the ult to end the channel as well would make Nunu's kit feel much better.