save project

my_tree.py

 import turtle
+import random
+def tree(n):
+    if n >= 50:
+        pen.forward(n)
+        a = random.randint(0,30)
+        pen.right(a)
+        tree(n-10)
+        pen.left(2*a)
+        tree(n-10)
+        pen.right(a)
+        pen.up()
+        pen.backward(n)
+        pen.down()
 
 pen = turtle.Turtle()
 pen.color('sienna')
@@ -11,5 +24,5 @@ pen.left(90)
 pen.up()
 pen.backward(150)    # 后退
 pen.down()
-
+tree(100)
 turtle.done()