A sequencer is a throttle that is specialized to only allow one job at a time and to, by default, not continue on error.
include sig ... end
val sexp_of_t : ('a ‑> Base.Sexp.t) ‑> 'a t ‑> Base.Sexp.t
val create : ?continue_on_error:bool ‑> 'a ‑> 'a t