Suffix

After this patch, A_min set minimum for A, A_max set maximum for A,
A_fixed set fixed value for A, which means will not covered by setting after it.

This feature is useful when we set a parameter and do not want it covered by
new value late.

We need it when running case in loops.

@will-Do The cartesian_config.py can be used to execute directly to debug the problems we make in cfg files. So we don't want it to import any modules in autotest