llows you to specify the amount in which each event is shifted. @pressBy 0.5@ is the same as @press@, while @pressBy (1/3)@ shifts each event by a third of its arc.
pressBy :: Pattern Time -> Pattern a -> Pattern a
pressBy = tParam _pressBy

_pressBy :: Time -> Pa
pressBy :: Pattern Time -> Pattern a -> Pattern a
pressBy = tParam _pressBy
pressBy = tParam _pressBy