Dllist

`sig type 'a node_t exception Empty val create : 'a -> 'a Dllist.node_t val copy : 'a Dllist.node_t -> 'a Dllist.node_t val length : 'a Dllist.node_t -> int val rev : 'a Dllist.node_t -> unit val add : 'a Dllist.node_t -> 'a -> unit val append : 'a Dllist.node_t -> 'a -> 'a Dllist.node_t val prepend : 'a Dllist.node_t -> 'a -> 'a Dllist.node_t val promote : 'a Dllist.node_t -> unit val demote : 'a Dllist.node_t -> unit val remove : 'a Dllist.node_t -> unit val drop : 'a Dllist.node_t -> 'a Dllist.node_t val rev_drop : 'a Dllist.node_t -> 'a Dllist.node_t val splice : 'a Dllist.node_t -> 'a Dllist.node_t -> unit val get : 'a Dllist.node_t -> 'a val set : 'a Dllist.node_t -> 'a -> unit val next : 'a Dllist.node_t -> 'a Dllist.node_t val prev : 'a Dllist.node_t -> 'a Dllist.node_t val skip : 'a Dllist.node_t -> int -> 'a Dllist.node_t val iter : ('a -> unit) -> 'a Dllist.node_t -> unit val fold_left : ('a -> 'b -> 'a) -> 'a -> 'b Dllist.node_t -> 'a val fold_right : ('a -> 'b -> 'b) -> 'a Dllist.node_t -> 'b -> 'b val map : ('a -> 'b) -> 'a Dllist.node_t -> 'b Dllist.node_t val to_list : 'a Dllist.node_t -> 'a list val of_list : 'a list -> 'a Dllist.node_t val enum : 'a Dllist.node_t -> 'a Enum.t val rev_enum : 'a Dllist.node_t -> 'a Enum.t val of_enum : 'a Enum.t -> 'a Dllist.node_t end`