public function propagate(node $node, $parent, $parentID)
 {
     $node->parent = $parent;
     $node->parentID = $parentID;
     $node->gCostOfParent = $node->getGCostOfParent();
     $node->gCostToParent = $node->getGCostToParent();
     $node->gTotal = $node->calculateTotalGCost();
     $node->fValue = $node->calculateFValue();
 }