Kernel language representation of a function

What is the kernel language representation of N + {Add N - 1} following the stub

local I1 in

// the code

        end
    end
end

the procedure definition of function {Add N} is as follows

proc {Add N R}
    if N == 0 then R = 0
    else N + {Add N - 1}
    end
end

In the kernel language, you have to define a new identifier for each operation. One for the N-1 operation, another to retrieve the result of the procedure Add and a third one to store the result of N + {Add N-1}. Also you have to declare each local variable separately.

So you get something like this :

local I1 in
   local I2 in
      local I3 in
         I1 = 1
         I2 = N - I1
         {Add I2 I3}
         R = N + I3
      end
   end
end

Then I3 contains the value N + {Add N-1}