module Make_var_type:
Creates get and set like make_var_type. Call it like
         module Foo_var = 
           Make_var_type(struct t = foo end)
      and use Foo_var.get and Foo_var.set to access the container
      variables of type foo.
| Parameters: | 
 | 
type 
val get : string -> t
val set : string -> t -> unit