average 3 similar frames

[Dogway]

Hello.

I'm trying to average all continuous 3 similar frames on my source, this is typical on anime footage where you find patterns of 2 or 3 repeated cel frames. Something is not entirely correct on my try, it says "RAverageW: Averaging arguments need to be in pairs"

ScriptClip("
diff1 = YDifferenceFromPrevious()
diff2 = YDifferenceToNext()
chunk = SelectRangeEvery(current_frame, 3, 0)
T = chunk.RAverageW(selectevery(3,0), 0.33, selectevery(3,1), 0.34,selectevery(3,2),0.33)
T = interleave(T,T,T)
diff1 + diff2 > 1.2 ? last : T")

I'm aware that selectrangevery() is not correct here either. I also tried with selectevery(1,-1), selectevery(1,0), selectevery(1,1) on RAverageW.