save project

my_tree.py

@@ -11,12 +11,17 @@ def tree(n):
     if n>=0:
         pen.forward(n)
         pen.right(30)
-        tree(n)
-        pen.forward(n-10)
-        tree(n)
-        pen.up()
-        pen.backward(n-10)
+        tree(n-10)
         pen.left(60)
+        tree(n-10)
+        pen.right(30)
+        pen.up()
+        pen.backward(n)
         pen.down()
+pen.left(90)
+pen.up()
+pen.backward(150)    # 后退
+pen.down()
 tree(100)
+
 turtle.done()