code: func (dt *decisionTree) orderedNodes(meetsConstraints func(*NodeInfo) bool, nodeLess func(*NodeInfo, *NodeInfo) bool) []NodeInfo {
  	if dt.nodeHeap.length != len(dt.nodeHeap.nodes) {
  		// We already collapsed the heap into a sorted slice, so
  		// re-heapify. There may have been modifications to the nodes
  		// so we can't return dt.nodeHeap.nodes as-is. We also need to
  		// reevaluate constraints because of the possible modifications.
  		for i := 0; i < len(dt.nodeHeap.nodes); {
  			if meetsConstraints(&dt.nodeHeap.nodes[i]) {
  				i++
  			} else {
  				last := len(dt.nodeHeap.nodes) - 1
  				dt.nodeHeap.nodes[i] = dt.nodeHeap.nodes[last]
  				dt.nodeHeap.nodes = dt.nodeHeap.nodes[:last]
  			}
  		}
  		dt.nodeHeap.length = len(dt.nodeHeap.nodes)
  		heap.Init(&dt.nodeHeap)
  	}
  
  	// Popping every element orders the nodes from best to worst. The
  	// first pop gets the worst node (since this a max-heap), and puts it
  	// at position n-1. Then the next pop puts the next-worst at n-2, and
  	// so on.
  	for dt.nodeHeap.Len() > 0 {
  		heap.Pop(&dt.nodeHeap)
  	}
  
  	return dt.nodeHeap.nodes
  }
docs: // orderedNodes returns the nodes in this decision tree entry, sorted best
  // (lowest) first according to the sorting function. Must be called on a leaf
  // of the decision tree.
  //
  // The caller may modify the nodes in the returned slice.