'Deletes the pending notification with the given timestamp.
Args:
timestamp: The timestamp of the notification. Assumed to be unique.
Raises:
UniqueKeyError: Raised if multiple notifications have the timestamp.'

def DeletePendingNotification(self, timestamp):

    shown_notifications = self.Get(self.Schema.SHOWN_NOTIFICATIONS)
    if (not shown_notifications):
        shown_notifications = self.Schema.SHOWN_NOTIFICATIONS()
    pending = self.Get(self.Schema.PENDING_NOTIFICATIONS)
    if (not pending):
        return
    delete_count = 0
    for idx in reversed(range(0, len(pending))):
        if (pending[idx].timestamp == timestamp):
            shown_notifications.Append(pending[idx])
            pending.Pop(idx)
            delete_count += 1
    if (delete_count > 1):
        raise UniqueKeyError(('Multiple    notifications    at    %s' % timestamp))
    self.Set(self.Schema.PENDING_NOTIFICATIONS, pending)
    self.Set(self.Schema.SHOWN_NOTIFICATIONS, shown_notifications)
