code: def delete_thing(self, thing):
          
          try:
              self.things.remove(thing)
          except ValueError, e:
              print e
              print "  in Environment delete_thing"
              print "  Thing to be removed: %s at %s" % (thing, thing.location)
              print "  from list: %s" % [(thing, thing.location)
                                         for thing in self.things]
          if thing in self.agents:
              self.agents.remove(thing)
docs: Remove a thing from the environment.