anchor.diff:  
     /**
      * Changes the length of the list. If [newLength] is greater than
  -   * the current [length], entries are initialized to [:null:]. Throws a
  -   * [UnsupportedOperationException] if the list is not extendable.
  +   * the current [length], entries are initialized to [:null:]. Throws
  +   * an [UnsupportedOperationException] if the list is not extendable.
      */
     void set length(int newLength);
   
     /**
      * Adds [value] at the end of the list, extending the length by
  -   * one. Throws a [UnsupportedOperationException] if the list is not
  +   * one. Throws an [UnsupportedOperationException] if the list is not
      * extendable.
      */
     void add(E value);
   
     /**
      * Adds [value] at the end of the list, extending the length by
  -   * one. Throws a [UnsupportedOperationException] if the list is not
  +   * one. Throws an [UnsupportedOperationException] if the list is not
      * extendable.
      */
     void addLast(E value);
  
positive.code: 
    /**
     * Removes all elements in the list. The length of the list
     * becomes zero. Throws a [UnsupportedOperationException] if
     * the list is not extendable.
     */
    void clear();
  
negative.code:   E last();
  
    /**
     * Returns a sub list copy of this list, from [start] to
     * [:start + length:].
     * Throws an [IndexOutOfRangeException] if [start] or
     * [:start + length:] are out of range.
     */
    List<E> getRange(int start, int length);
  
    /**
     * Copies [length] elements of the [from] array, starting
     * from [startFrom], into [:this:], starting at [start].
     * Throws an [UnsupportedOperationException] if the list is
     * not extendable.
     * Throws an [IndexOutOfRangeException] if [start] or
     * [:start + length:] are out of range for [:this:], or if
     * [startFrom] is out of range for [from].
     */
    void setRange(int start, int length, List<E> from, [int startFrom]);
  
    /**
     * Removes the range in the list starting from [start] to
     * [:start + length:].
     * Throws an [UnsupportedOperationException] if the list is
     * not extendable.
     * Throws an [IndexOutOfRangeException] if [start] or
     * [:start + length:] are out of range.
     */
    void removeRange(int start, int length);
  
    /**
     * Inserts a new range in the list, starting from [start] to
     * [:start + length:]. The entries are filled with [initialValue].
     * Throws an [UnsupportedOperationException] if the list is
     * not extendable.
     * Throws an [IndexOutOfRangeException] if [start] or
     * [:start + length:] are out of range.
     */
    void insertRange(int start, int length, [E initialValue]);
  }
  