save project

my_tree.py

@@ -11,5 +11,18 @@ pen.left(90)
 pen.up()
 pen.backward(150)    # 后退
 pen.down()
+def darw_tree(n,lenth):
+    if n==1:
+      pen.forward(lenth)
+      pen.backward(lenth)
+    else:
+        pen.forward(lenth)
+        pen.right(30)
+        darw_tree(n-1,lenth/2)
+        pen.left(60)
+        darw_tree(n-1,lenth/2)
+        pen.right(30)
+        pen.backward(lenth)
 
+darw_tree(2)
 turtle.done()