Maybe_explicit.Bothtype 'a maybe_explicit := 'a tval create : (explicitness -> 'a) -> 'a tval extract_list : 'a t -> 'a listval opt_map : 'a t -> f:('a -> 'b option) -> 'b opt_map_resultval opt_fold_map :
'a t ->
init:'b ->
f:('b -> 'a -> 'b * 'c option) ->
'b * 'c opt_map_result