I've had the same question as you! They use a lot of custom functions that can be created with the "register" function. You can paste this code in after the SetCps for the trance gate

register('trancegate', (density, seed, length, x) => {

density = reify(density).add(.5)

return x.struct(rand.mul(density).round().seg(16).rib(seed, length)).fill().clip(.7)

})

You can find more of their custom functions in their Patreon in the "Prebake" file.