anchor.diff:    /// is greater than or equal to its value.
     NodePair<T> insert(RedBlackNode<T> node);
   
  -  /// Inserts [node] after [after].  If [after] is null, [node] will become the
  -  /// new head of the list. If [after] is [tail], [node] will become the new
  -  /// tail of the list.
  +  /// Inserts [node] after [after] and returns a [NodePair] where first = the
  +  /// parent of [node] and second = [node].  
     /// 
  -  /// Returns a [NodePair] whose first getter is the parent of [node] and whose
  -  /// second getter is [node].
  -  /// 
  -  /// If [after] is null then [node] is inserted at the root of the tree.
  -  /// 
  +  /// If [after] is null or [head] then [node] will become the new head of the 
  +  /// list. If [after] is [tail], [node] will become the new tail of the list.
  +  ///
     /// It is recommeneded to use [insert] as this function allows you to violate
     /// the sorted order of the linked-list.
     NodePair<T> insertAfter(RedBlackNode<T> after, RedBlackNode<T> node);
  
positive.code:   /// Returns a NodePair representing a location for [value] to be inserted into
    /// the tree as a leaf. 
    /// 
    /// The node property will be null and the parent property
    /// will contain the would-be parent of [value]'s node if it were inserted
    /// into the tree.
    NodePair<T> findInsertionPoint(T value);
  
    /// Inserts [node] into the tree as a leaf.
  
negative.code: /// - Returns 0 when lhs and rhs are ordered equally.
  typedef int Comparator(T lhs, T rhs);
  
  /// A pair of [RedBlackNode]s. Used as the result of read/write operations on a
  /// [RedBlackTree].
  class NodePair<T> {
    final RedBlackNode<T> first;
  