Swap complementary Integer calls for their opposite:
Integer.mod↔Integer.floor_div— the two halves of floored division (modis the remainder,floor_divthe quotient); confusing one for the other is a classic off-by-operation bugInteger.is_even↔Integer.is_odd— the parity predicates
The integer-call sibling of Mutare.Mutators.Numeric/Math (and named like Mutare.Mutators.StringCall beside the Mutare.Mutators.IntegerLiteral value family, to keep "calls to Integer" distinct from "integer literals").
Integer.is_even/is_odd are guard-safe macros, so a swap in a when clause is mutated too. On by default. Matches aliased and bare-imported calls (alias Integer, as: I; I.is_even → I.is_odd), while a shadowing alias MyApp.Integer is left alone.