Reads notifications scheduled for a user within a given timerange.

def ReadUserNotifications(self, username, state=None, timerange=None):
    """Reads notifications scheduled for a user within a given timerange."""
    from_time, to_time = self._ParseTimeRange(timerange)

    result = []
    for n in self.notifications_by_username.get(username, []):
      if from_time <= n.timestamp <= to_time and (state is None or
                                                  n.state == state):
        result.append(n.Copy())

    return sorted(result, key=lambda r: r.timestamp, reverse=True)