type t = (string, string) Core.Std.List.Assoc.t
val add : key:string -> data:string -> t -> t
val find : key:string -> t -> string option
val find_exn : key:string -> t -> string
val mem : key:string -> t -> bool
val remove : key:string -> t -> t
val import_from_sys : ?default:string -> key:string -> t -> t
val append_to_path : ?where:[ `Back | `Front ] -> key:string -> data:string -> t -> t
val to_exec_env : t -> string list
val of_exec_env : string array -> t