auto save

my_tree.py

 import turtle
+import random
+#随机树杈角度  随机树干长度 慢慢变小树枝 
+turtle.speed(0)
+def tree(n): #90 80
+    if n>=20:
+        pen.pensize(n/10)
+        a=random.randint(1,30)
+        b=random.randint(1,15)
+        pen.fd(n)
+        pen.right(a)
+        tree(n-b)
+        pen.left(a*2)
+        tree(n-b)   # tree(100-10) tree(90-10)
+        pen.right(a)
+        pen.up()
+        pen.backward(n)
+        pen.down()
+
 
 pen = turtle.Turtle()
 pen.color('sienna')
@@ -12,4 +30,6 @@ pen.up()
 pen.backward(150)    # 后退
 pen.down()
 
+tree(60)
+
 turtle.done()