test.ps

@declarations
declare number 0
declare current_number 0
declare temp 0
declare fn 0
declare fnp1 1
@declarations

@functions
function iterate_once {
    change temp fn
    change fn fnp1
    change fnp1 !fnp1 + temp!
    change current_number !current_number + 1!
}
@functions

@body
show `enter an integer, n`
capture number

while |current_number < number|
{
    run iterate_once
}

show `the nth fibonacci number is`
show fn
@body