def method_missing(meth, *args)
      if include?(meth.to_s) then
        if args.empty? then
          create_getter meth
        else
          raise ArgumentError, "wrong number of arguments (#{args.size} for 0)"
        end
      elsif meth.to_s =~ /^(.+)\?$/ and include?(root_meth = $1) then
        if args.empty? then
          !!create_getter(root_meth) #TODO duplication of logic
        else
          raise ArgumentError, "wrong number of arguments (#{args.size} for 0)"
        end
      else
        super
      end
    end
def method_missing(meth, *args)
      if include?(meth.to_s) then
        if args.empty? then
          create_getter meth
        else
          raise ArgumentError, "wrong number of arguments (#{args.size} for 0)"
        end
      elsif meth.to_s =~ /^(.+)\?$/ and include?(root_meth = $1) then
        if args.empty? then
          !!create_getter(root_meth) #TODO duplication of logic
        else
          raise ArgumentError, "wrong number of arguments (#{args.size} for 0)"
        end
      else
        super
      end
    end
@private

 To optimize access, we create a getter method every time we encounter a
 key that exists in the hash. If the key is later deleted, the method will
 be removed.