Solution: Inferred function types

Centimeter::plus function type is (Centimeter, Centimeter) -> Centimeter

Centimeter::times function type is (Centimeter, Double) -> Centimeter

Centimeter::value function type is (Centimeter) -> Double

Centimeter::toString function type is (Centimeter) -> String

Centimeter(1.0)::plus function type is (Centimeter) -> Centimeter

Centimeter(2.0)::times function type is (Double) -> Centimeter

Centimeter(3.0)::value function type is () -> Double

Centimeter(4.0)::toString function type is () -> String

Int::cm function type is (Int) -> Centimeter

123::cm function type is () -> Centimeter

::distance function type is (Centimeter, Centimeter) -> Centimeter