auto save

my_tree.py

+import turtle
+import random 
+pen = turtle.Turtle
+pen.color("sienna")
+pen.speed(0)
+w=turtle.Screen()
+w.bgcolor("wheat")
+pen.left(90)
+pen.up()
+pen.backward(150)    # 后退
+pen.down()
+ 
+def tree(n):
+    if n >= 0:
+        if n <=12:
+            color_list = ['snow', 'lightcoral']
+            color=random.choice(color_list)
+            pen.color(color)
+            pen.pensize(n/3)
+        else:
+            pen.color('sienna')
+            pen.pensize(n/10)
+        pen.forward(n)
+        angle=random.random()
+        pen.right(30*angle)
+        length=1.5*random.random()
+        tree(n-10*length)
+        pen.left(60*angle)
+        tree(n-10*length)
+        pen.right(30*angle)
+        pen.up()
+        pen.backward(n)
+        pen.down()
+
+tree(60)
+
+
+turtle.done()