Synchronizing simultaneous and sequential music to create a simple 140 bpm music-loop manager

There are times when we need to precisely schedule audio start times to ensure a smooth transition from one music track to another or to ensure simultaneous music tracks play in time together.

In this recipe, we'll create a simple 4-track 140 bpm music manager that starts playing a new sound after a fixed time – the result of which is that the tracks fit together perfectly, and those that do overlap do so in synchronicity.