It's stack based, like Forth and RPN. So 1 2 3 * + means something like

    push(1); push(2); push(3); multiply-top-of-the-stack(); add-top-of-the-stack();

So `status pls` means: call the function status (which leaves its results on the stack) and print the top of the stack with new-lines (multiple lines if it's an array).

Then `status upcase pls` would do something like the above, but it calls a "to uppercase" function before printing.