Размер окна(hw) и шаг(step) лестницы, если надо, можно изменить
Python
import tkinter
hw=580
step=20
master = tkinter.Tk()
canvas = tkinter.Canvas(master, bg='white', height=hw, width=hw)
canvas.pack()
points = []
points2 = []
for x in range (0+step, hw, step):
points.append((x,hw - x +step))
points.append((x,hw - x))
points.append((hw,hw - x))
canvas.create_line(points, fill = 'blue', width=2)
points2.append((2*step,hw))
points2.append((hw,2*step))
canvas.create_line(points2, fill = 'blue', width=2)
master.mainloop()
