anchor.diff:    /// ```
     Token parseForInRest(
         Token awaitToken, Token forKeyword, Token leftParenthesis, Token token) {
  +    // TODO(brianwilkerson) Accept the last consumed token.
  +    // TODO(brianwilkerson) Return the last consumed token.
       assert(optional('in', token) || optional(':', token));
       Token inKeyword = token;
       token = token.next;
  
positive.code:   /// ;
    /// ```
    Token parseSwitchBlock(Token token) {
      Token begin = token;
      listener.beginSwitchBlock(begin);
      token = expect('{', token);
  
negative.code:   /// ;
    /// ```
    Token parseMapLiteralEntry(Token token) {
      // TODO(brianwilkerson) Accept the last consumed token.
      // TODO(brianwilkerson) Return the last consumed token.
      listener.beginLiteralMapEntry(token);
      // Assume the listener rejects non-string keys.
      // TODO(brianwilkerson): Change the assumption above by moving error
  