save project

my_tree.py

@@ -12,15 +12,16 @@ pen.up()
 pen.backward(150)    # 后退
 pen.down()
 def tree(n):
-    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()
+    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()