# square_variable.py
from turtle import *

pensize(4)
line_length = 25  # This variable stores the number 25.
forward(line_length)  # The turtle moves 25 steps because line_length is 25.
left(90)
forward(line_length)
left(90)
forward(line_length)
left(90)
forward(line_length)
left(90)
done()