# File lib/rhc/vendor/okjson.rb, line 373
      def subst(u1, u2)
        if Usurr1 <= u1 && u1 < Usurr2 && Usurr2 <= u2 && u2 < Usurr3
          return ((u1-Usurr1)<<10) | (u2-Usurr2) + Usurrself
        end
        return Ucharerr
      end