module type Creators1 =sig..end
type 'a t 
type 'a tree 
type key 
val empty : 'a tval singleton : key -> 'a -> 'a tval of_alist : (key * 'a) list ->
       [ `Duplicate_key of key
       | `Ok of 'a t ]val of_alist_exn : (key * 'a) list -> 'a tval of_alist_multi : (key * 'a) list -> 'a list tval of_alist_fold : (key * 'a) list ->
       init:'b -> f:('b -> 'a -> 'b) -> 'b tval of_sorted_array : (key * 'a) array ->
       'a t Or_error.tval of_sorted_array_unchecked : (key * 'a) array -> 'a tval of_tree : 'a tree -> 'a t