Stop casting in LUA

[provocating]

I want to stop the casting of a spell in LUA. I will finish this script out once I can at least get the spell to stop, not worried about that yet, I know how to get the spell ID and I will filter it from there. How do you get a a spell to stop casting though? I am not seeing a client interrupt function out there. I think stop just stops an NPC from moving on it's waypoint and has nothing to do with spells.

function event_cast_begin(e)
    e.self:stop();
end