 Apply a function to a mixed amount's quantities (and its total prices, if it has any).
transformMixedAmount :: (Quantity -> Quantity) -> MixedAmount -> MixedAmount
transformMixedAmount f = mapMixedAmountUnsafe (transformAmount f)

--
transformMixedAmount :: (Quantity -> Quantity) -> MixedAmount -> MixedAmount
transformMixedAmount f = mapMixedAmountUnsafe (transformAmount f)
transformMixedAmount f = mapMixedAmountUnsafe (transformAmount f)