save project

my_tree.py

@@ -11,5 +11,16 @@ pen.left(90)
 pen.up()
 pen.backward(150)    # 后退
 pen.down()
-
+def tree(n):
+    if n>=50:
+        pen.forward(n)
+        pen.right(30)
+        tree(n-50)
+        pen.left(60)
+        tree(n-50)
+        pen.right(30)
+        pen.up()
+        pen.backward(n)
+        pen.down()
+tree(100)
 turtle.done()