module Top:sig
..end
type'a
or_top_bottom =[ `Bottom | `Top | `Value of 'a ]
val join : ('a -> 'a -> 'a) ->
'a or_top_bottom ->
'a or_top_bottom -> 'a or_top_bottom
val narrow : ('a -> 'a -> 'a or_bottom) ->
'a or_top_bottom ->
'a or_top_bottom -> 'a or_top_bottom