* @param unit The <code>Unit</code> to be put out.
     * @return An <code>Element</code> encapsulating this action.
     */
    public Element putOutsideColony(ServerPlayer serverPlayer, Unit unit) {
        Tile tile = unit.getTile();
        Colony colony = unit.getColony();
        unit.setLocation(tile);

        // Full tile update for the player, the rest get their limited
        // view of the colony so that population changes.
        ChangeSet cs = new ChangeSet();
        cs.add(See.only(serverPlayer), tile);
        cs.add(See.perhaps().except(serverPlayer), colony);
        return cs.build(serverPlayer);
    }