worm.kill(): remove from arena.worms at this point, rather than relying on the...

worm.kill(): remove from arena.worms at this point, rather than relying on the try/finally in the thread.

docs/tutorial/worms.py

@@ -63,10 +63,14 @@ class arena:
             x, y = self.random_pos()
             self.worms.append (worm (self, x, y))
     def cull (self, hoffa=False):
+        removed = []
         for worm in self.worms:
             if worm.stunned:
                 W ('culling worm %r\n' % (worm.chr,))
                 worm.kill (hoffa)
+                removed.append (worm)
+        for r in removed:
+            self.worms.remove (r)
 
 class worm:
 
@@ -91,7 +95,6 @@ class worm:
         coro.spawn (self.go)
         
     def go (self):
-        try:
         while not self.exit:
             coro.sleep_relative (self.speed / 10000.0)
             if random.randrange (0,20) == 10:
@@ -104,8 +107,6 @@ class worm:
                         return
                     nx, ny = self.update()
                 self.move ((nx, ny))                        
-        finally:
-            self.arena.worms.remove (self)
 
     def update (self):
         x, y = self.head