My Countdown Script

#!/bin/python3

from sense_hat import SenseHat
from time import sleep

countdowner = SenseHat()

G = [0, 255, 0]
R = [255, 0, 0]
X = [0,0,0]

s = 20 # number of seconds  play with this to chnage the numbe rof dots (leds)

timer = [] #an empty list

for i in range(64):  # same as for i in range(0, 64)
  if i < s:
    timer.append(G)
    # print(i, timer)
  else:
    timer.append(X)
    # print(i, timer)

countdowner.set_pixels(timer)
#print(timer)

for i in range(0, s):
  sleep(1)
  timer[i] = R
  countdowner.set_pixels(timer)

for i in range(0,10):
  countdowner.clear()
  sleep(0.1)
  countdowner.set_pixels(timer)
  sleep(0.1)