     if let linkView = linkViews[link.identifier] {
       linkView.needsDisplay = true
     } else {
+      sprint("draw new link view for \(link)")
       let linkView = LinkView(link: link, canvas: self)
       addSubview(linkView)
       linkViews[link.identifier] = linkView

    newConcept = nil
  }
  
  // MARK: - CanvasLinkActions
  
  func drawLinkViews() {

  
  func conceptViewFor(concept: Concept) -> ConceptView {
    return conceptViews[concept.identifier]!
  }
  
  func linkViewFor(link: Link) -> LinkView {
    return linkViews[link.identifier]!
  }

  // MARK: - CanvasConceptsActions
