Added some comments to the file for clarity.
Added commands, and the "use blanks" command.
Now uses RegExps to extract variables.
Now uses regexp when simpler in find_exps(..)
Now parses the command using regexp (simpler)
Rewrote gen_part_array(..) to use regexp. Way simpler/clearer now.
Added the "random" keyword:

if you add random before a list of elements, in will display them in random order.