User blog comment:Hyp cos/Analysis - BEAF, FGH and SGH (part 3)/@comment-24509095-20140626092059/@comment-5150073-20140626151551

With this trick, all this is legal. And in fact, by standard rules, we must "lengthen" $$\psi(I*2)$$ to $$\psi(\psi_I(I*2))$$, not to $$\psi(\psi_I(I)*2)$$.