save project

my_tree.py

@@ -13,9 +13,12 @@ pen.up()
 pen.backward(150)    # 后退
 pen.down()
 def t(n):
-    pen.forward(n)
-    pen.right(30)
-    t(n-10)
-    pen.left(60)
-    t(n-10)
+    if n>0:
+        pen.forward(n)
+        pen.right(30)
+        t(n-10)
+        pen.left(60)
+        t(n-10)
+        pem.backward(n)
+t(50)
 turtle.done()