   }
 }
 
-public class QuadTree: PointsContainter {
+public class QuadTree: PointsContainer {
   
   let root: QuadTreeNode
   

  }
}

protocol PointsContainter {
  func add(point: Point) -> Bool
  func points(inRect rect: Rect) -> [Point]
}

  }
}

extension QuadTreeNode: PointsContainer {
  
  @discardableResult
  func add(point: Point) -> Bool {
