auto save

my_tree.py

 import turtle
 import turtle
 def tree(n)
 def tree(n)
     if n>=50
     if n>=50
-        pen.forward()
+        pen.pensize(n/10)
+        pen.forward(n)
         angle=random.randint(0,30)
         angle=random.randint(0,30)
         length=random.randint(1,15)
         length=random.randint(1,15)
         pen.right(angle)
         pen.right(angle)
-        tree(n-angle)
+        tree(n-10)
         pen.left(2*angle)
         pen.left(2*angle)
-        tree(n-angle)
+        tree(n-10)
         pen.right(angle)
         pen.right(angle)
         pen.up()
         pen.up()
         pen.backward(n)    # 后退
         pen.backward(n)    # 后退