Result is Number1 * Number2
    which should be preferred for portability.
The result is of type breal if any of the arguments is a breal, else float if any of the arguments is a float, else rational if any of the arguments is a rational. Only when both arguments are integers is the result an integer.
In coroutining mode, if Number1 or Number2 are uninstantiated, the call to */3 is delayed until these variables are instantiated.
Success:
      *(5, 2, 10).
      *(5, -2.0, -10.0).
Fail:
      *(1, 2, 3).
      *(5, 2, 10.0).
      *(5, 2.0, 10).
      *(1, 2, 3.0).
      *(5, 2, r).
Error:
      *(A, 2, 6).             (Error 4).
      *(4 + 2, 2, 12).        (Error 24).