Stack trace

ruslan@TFTM-K53TA:~/Programming/python/pygame/pyscroll/tests$ python demo.py
no TMX map specified, using default
Traceback (most recent call last):
  File "demo.py", line 130, in <module>
    test.run()
  File "demo.py", line 107, in run
    self.update(dt)
  File "demo.py", line 86, in update
    self.map_layer.center(self.center)
  File "build/bdist.linux-x86_64/egg/pyscroll/pyscroll.py", line 164, in center
  File "build/bdist.linux-x86_64/egg/pyscroll/pyscroll.py", line 189, in queue_edge_tiles
  File "build/bdist.linux-x86_64/egg/pyscroll/pyscroll.py", line 36, in visible_layers
AttributeError: 'TiledMap' object has no attribute 'visible_layers'