function _cascadingCut(minimum, node) {
    // store parent node
    var parent = node.parent; // if there's a parent...

    if (!parent) {
      return;
    } // if node is unmarked, set it marked


    if (!node.mark) {
      node.mark = true;
    } else {
      // it's marked, cut it from parent
      _cut(minimum, node, parent); // cut its parent as well


      _cascadingCut(parent);
    }
  }
Performs a cascading cut operation. This cuts node from its parent and then
does the same for its parent, and so on up the tree.
Running time: O(log n); O(1) excluding the recursion.
@memberof FibonacciHeap