class virtual [['a, 'b]] next : object .. end
[['a, 'b]]
object
end
inherit ['i, 'o] next
method private virtual guard : ('a, 'b, unit) guard
('a, 'b, unit) guard
method next : 'c. ('a, 'b, 'c) t
'c. ('a, 'b, 'c) t
obj#next
Cf_state_gadget.guard
self#guard