code: function(instance, searchNode, x, y, cost) {
          var adjacentCoordinateX = searchNode.x+x;
          var adjacentCoordinateY = searchNode.y+y;
  
          if ((pointsToAvoid[adjacentCoordinateY] === undefined ||
               pointsToAvoid[adjacentCoordinateY][adjacentCoordinateX] === undefined) &&
              isTileWalkable(collisionGrid, acceptableTiles, adjacentCoordinateX, adjacentCoordinateY, searchNode)) {
              var node = coordinateToNode(instance, adjacentCoordinateX,
                  adjacentCoordinateY, searchNode, cost);
  
              if (node.list === undefined) {
                  node.list = OPEN_LIST;
                  instance.openList.push(node);
              } else if (searchNode.costSoFar + cost < node.costSoFar) {
                  node.costSoFar = searchNode.costSoFar + cost;
                  node.parent = searchNode;
                  instance.openList.updateItem(node);
              }
          }
      }
docs: Private methods follow