Simple command line application using tapCreate(tap:place:options:eventsOfInterest:callback:userInfo:) to negate the values for events of the CGEventType.scrollWheel type that are not continuous.
Effectively this reverses the annoying coupling of mouse and trackpad Scroll direction: Natural settings starting with macOS Mojave, allowing the trackpad to have natural scrolling and the mouse nominal scrolling.
swiftc -target x86_64-apple-darwin18 au-naturel.swift