checking in

I can't quite get the game to work. It keeps crashing when the
asteroid gets to the bottom.

asteroid.py

@@ -2,3 +2,22 @@
 # ------------
 # By MWC Contributors
 # This module defines an asteroid agent class.
+
+class Asteroid:
+    character = '0'
+
+    def __init__(self, position):
+        self.position = position
+
+    def play_turn(self,game):
+        if game.turn_number % 2 ==0:
+            x,y = self.position
+            if y == HEIGHT - 1: #need to rename as height
+                game.remove_agent_by_name(name.self)
+            else:
+                ship = game.get_agent_by_name('ship')
+                new_position = (x, y + 1)
+                if new_position == ship.position:
+                    game.end()
+                else:
+                    self.position = new_position