from turtle import *

def draw_tile(size):
    "Draws one tile, which can be repeated to form a pattern."
    draw_tile_outline(size)
    draw_fancysquiggle(size)

def draw_tile_outline(size):
    pencolor("#dddddd")
    square(size)

def draw_fancysquiggle(size):
    pencolor("blue")
    left(90)
    half_arc_right(size/2)
    left(180)
    fly(size/2)
    left(90)
    fly(size/2)
    right(90)
    pencolor("red")
    forward(size/2)
    left(90)
    fly(size/2)
    left(90)
    fly(size)
    left(90)

def fly(distance):
    "Moves without drawing."
    penup()
    forward(distance)
    pendown()

def square(size):
    "Draws a square of side length `size`"
    for side in range(4):
        forward(size)
        left(90)

def half_arc_right(radius):
    "Draws a half of an arc, turning to the right."
    circle(-radius, 180)

def half_arc_left(radius):
    "Draws a half of an arc, turning to the left."
    circle(radius, 180)