sig val more : ('i Cf_seq.t option, 'o) Cf_flow.t -> 'i Cf_seq.t -> 'o Cf_seq.t * ('i Cf_seq.t option, 'o) Cf_flow.t val last : ('i Cf_seq.t option, 'o) Cf_flow.t -> 'o Cf_seq.t end