auto save

p.py

+import turtle
+screen=turtle.Screen()
+screen.bgcolor("black")
+colors=["yellow","blue","red","green"]
+pen = turtle.Pen()
+pen.speed(120)
+for i in range(1,300):
+    pen.pencolor(colors[i%4])
+    pen.forward(i)
+    pen.right(91)
+# 隐藏画笔，保存画布
+pen.hideturtle()
+turtle.done()