Ok, now that we have returned from the COMMAND/C tree example, lets try it
again using CALL.

Our top-level batch file is CALL0.BAT, which simply CALLs on CALL1.BAT and
so on on down to CALL3.BAT.

Now notice the fact that only a little less than 100 bytes of memory is
used by each level of call, simply to keep track of where to resume on
the completion of each CALLed module.