'Return the status of this order. Can be one of these: "open", "completed", "expired" or "cancelled"
:return: The status of this order
:rtype: str'

@property
def status(self):

    if self._cancelled:
        return 'cancelled'
    elif self.is_complete():
        return 'completed'
    elif self._timeout.is_timed_out(self._timestamp):
        return 'expired'
    return 'open'
