and attr = (string option * string * string) list
+val get_attr: 'a box -> attr
+val set_attr: attr -> 'a box -> 'a box
+
val smallskip : 'expr box
val skip: 'expr box
val indent : 'expr box -> 'expr box
val b_space: 'expr box
val b_kw: string -> 'expr box
+val pp_attr: attr -> string
+