Graded derivation ($Q(ab)=(Qa)b+(-1{)}^{|a|}a(Qb)$)

An odd graded derivation satisfies $Q(ab)=(Qa)b+(-1{)}^{|a|}a(Qb)$ for homogeneous $a$. Its square is an even derivation; consequently checking $Q^2=0$ on algebra generators establishes nilpotence everywhere.