auto save

my_tree.py

@@ -11,15 +11,20 @@ pen.left(90)
 pen.up()
 pen.backward(150)    # 后退
 pen.down()
-
-pen.pendown()
+#画二叉树
 pen.forward(100)
+#画右树枝
 pen.right(30)
 pen.forward(50)
-pen.penup()
+pen.up()
 pen.backward(50)
+pen.down()
+
+#画左树枝
 pen.left(60)
-pen.pendown()
 pen.forward(50)
+pen.up()
+pen.backward(50)
+pen.down()
 
 turtle.done()