how to make a time limit using renpy

1init:
2    $ timer_range = 0
3    $ timer_jump = 0

1transform alpha_dissolve:
2    alpha 0.0
3    linear 0.5 alpha 1.0
4    on hide:
5        linear 0.5 alpha 0
6    # This is to fade the bar in and out, and is only required once in your script
7
8screen countdown:
9    timer 0.01 repeat True action If(time > 0, true=SetVariable('time', time - 0.01), false=[Hide('countdown'), Jump(timer_jump)])
10    bar value time range timer_range xalign 0.5 yalign 0.9 xmaximum 300 at alpha_dissolve # This is the timer bar.