public function addDefense(Fleet $fleetDefender)
{
$fleetDefender->setTech($this->weapons_tech, $this->shields_tech, $this->armour_tech);
$this->order();
$fl = current($this->array);
if ($fl === false) {
$this->array[$fleetDefender->getId()] = $fleetDefender->cloneMe();
//avoid collateral effects: when the object or array is an argument && it's saved in a structure
} else {
$f->mergeFleet($fleetDefender);
}
}
