val (>>>) : ('i1, 'r1, 'incr, 'event) t -> ('r1, 'r2, 'incr, 'event) t -> ('i1, 'r2, 'incr, 'event) t
a >>> b
is compose a b
val (>>|) : ('input, 'r1, 'incr, 'event) t -> ('r1 -> 'r2) -> ('input, 'r2, 'incr, 'event) t
val (@>>) : ('i1 -> 'i2) -> ('i2, 'result, 'incr, 'event) t -> ('i1, 'result, 'incr, 'event) t