val is_empty : 'a Stdlib.Seq.t -> bool
val mapi : ( int -> 'a -> 'b ) -> 'a Stdlib.Seq.t -> 'b Stdlib.Seq.t
val unzip : ('a * 'b) Stdlib.Seq.t -> 'a Stdlib.Seq.t * 'b Stdlib.Seq.t
val append : 'a Stdlib.Seq.t -> 'a Stdlib.Seq.t -> 'a Stdlib.Seq.t
val drop : int -> 'a Stdlib.Seq.t -> 'a Stdlib.Seq.t