val map : ('a -> 'c) -> ('b -> 'd) -> ('a, 'b) union -> ('c, 'd) unionval equal :
('a -> 'a -> bool) ->
('b -> 'b -> bool) ->
('a, 'b) union ->
('a, 'b) union ->
boolval fold_left :
('c -> 'a -> 'c) ->
('c -> 'b -> 'c) ->
'c ->
('a, 'b) union ->
'c