388c388,390
<         return self._positions[0]
---
>         if len(self._positions):
>             return self._positions[0]
>         return None
392c394,397
<         self._positions = Places([pos])
---
>         if pos is None:
>             self._positions = Places([])
>         else:
>             self._positions = Places([pos])
423a429,430
>         if positions is None:
>             positions = Places([])