`sig
type 'a node_t = 'a BatDllist.node_t
type 'a t = 'a node_t
type 'a mappable = 'a t
type 'a enumerable = 'a t
exception Empty
val create : 'a -> 'a node_t
val copy : 'a node_t -> 'a node_t
val length : 'a node_t -> int
val rev : 'a node_t -> unit
val add : 'a node_t -> 'a -> unit
val append : 'a node_t -> 'a -> 'a node_t
val prepend : 'a node_t -> 'a -> 'a node_t
val promote : 'a node_t -> unit
val demote : 'a node_t -> unit
val remove : 'a node_t -> unit
val drop : 'a node_t -> 'a node_t
val rev_drop : 'a node_t -> 'a node_t
val splice : 'a node_t -> 'a node_t -> unit
val get : 'a node_t -> 'a
val set : 'a node_t -> 'a -> unit
val next : 'a node_t -> 'a node_t
val prev : 'a node_t -> 'a node_t
val skip : 'a node_t -> int -> 'a node_t
val iter : ('a -> unit) -> 'a node_t -> unit
val fold_left : ('a -> 'b -> 'a) -> 'a -> 'b node_t -> 'a
val fold_right : ('a -> 'b -> 'b) -> 'a node_t -> 'b -> 'b
val find : ('a -> bool) -> 'a node_t -> 'a node_t
val for_all : ('a -> bool) -> 'a node_t -> bool
val exists : ('a -> bool) -> 'a node_t -> bool
val map : ('a -> 'b) -> 'a node_t -> 'b node_t
val filter : ('a -> bool) -> 'a node_t -> 'a node_t
val filter_map : ('a -> 'b option) -> 'a node_t -> 'b node_t
val to_list : 'a node_t -> 'a list
val of_list : 'a list -> 'a node_t
val enum : 'a node_t -> 'a BatEnum.t
val rev_enum : 'a node_t -> 'a BatEnum.t
val backwards : 'a node_t -> 'a BatEnum.t
val of_enum : 'a BatEnum.t -> 'a node_t
val print :
?first:string ->
?last:string ->
?sep:string ->
('a BatInnerIO.output -> 'b -> unit) ->
'a BatInnerIO.output -> 'b t -> unit
val invariants : 'a t -> unit
end`