for i in range(10): # 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
    print(i + 1)

print("---")

x = 0
for i in range(20):
    x = i - x
print(x)

print("---")

for i in range(10, 0, -1):
    print(i)
    
print("---")

s = ""
for line in range(10, 14):
    s = s + str(line) + "-"
    print(s)
print(s)

print("---")

def isPrime(x):
    if x < 2:
        return False
    for factor in range(2, x):
        if x % factor == 0:
            return False
    return True

print(isPrime(37))
print(isPrime(27))

print("---")

def drawGrid(canvas, size):
    for row in range(size):
        top = row * 100
        bottom = top + 100
        for col in range(size):
            left = col * 100
            right = left + 100
            if row % 2 == 0:
                color = "red"
            else:
                color = "green"
            canvas.create_rectangle(left, top, right, bottom, fill=color)

import tkinter
def runDrawGrid():
    root = tkinter.Tk()
    canvas = tkinter.Canvas(root, width=800, 
                            height=800)
    canvas.configure(bd=0, 
                     highlightthickness=0)
    canvas.pack()

    drawGrid(canvas, 7) # your call here!

    root.mainloop()

runDrawGrid()