Turtle checkboard

#!/usr/bin/python

import turtle as t

if __name__ == '__main__':
    GRID_SIZE = 2
    SQUARE_SIZE = 60
    for row in range(GRID_SIZE):
        for col in range(GRID_SIZE):
            t.setpos(col * SQUARE_SIZE, row * SQUARE_SIZE)
            t.pendown()
            for i in range(4):
                t.forward(60)
                t.left(90)
            t.penup()