anchor.diff:    @override
     Source selectedSource;
   
  -  /**
  -   * Initialize a newly created namespace directive. Either or both of the
  -   * [comment] and [metadata] can be `null` if the directive does not have the
  -   * corresponding attribute. The list of [combinators] can be `null` if there
  -   * are no combinators.
  -   */
  +  /// Initialize a newly created namespace directive. Either or both of the
  +  /// [comment] and [metadata] can be `null` if the directive does not have the
  +  /// corresponding attribute. The list of [combinators] can be `null` if there
  +  /// are no combinators.
     NamespaceDirectiveImpl(
         CommentImpl comment,
         List<Annotation> metadata,
  
positive.code: }
  
  class SetLiteralImpl extends SetOrMapLiteralImpl implements SetLiteral {
    /**
     * Initialize a newly created set literal. The [constKeyword] can be `null` if
     * the literal is not a constant. The [typeArguments] can be `null` if no type
     * arguments were declared. The [elements] can be `null` if the set is empty.
     */
    SetLiteralImpl(Token constKeyword, TypeArgumentListImpl typeArguments,
        Token leftBracket, List<Expression> elements, Token rightBracket)
        : super._set(
  
negative.code:   }
  }
  
  /// An assignment expression.
  ///
  ///    assignmentExpression ::=
  ///        [Expression] operator [Expression]
  class AssignmentExpressionImpl extends ExpressionImpl
      implements AssignmentExpression {
    /// The expression used to compute the left hand side.
    ExpressionImpl _leftHandSide;
  
    /// The assignment operator being applied.
    @override
    Token operator;
  
    /// The expression used to compute the right hand side.
    ExpressionImpl _rightHandSide;
  
    /// The element associated with the operator based on the static type of the
    /// left-hand-side, or `null` if the AST structure has not been resolved, if
    /// the operator is not a compound operator, or if the operator could not be
    /// resolved.
    @override
    MethodElement staticElement;
  
    /// Initialize a newly created assignment expression.
    AssignmentExpressionImpl(ExpressionImpl leftHandSide, this.operator,
        ExpressionImpl rightHandSide) {
      if (leftHandSide == null || rightHandSide == null) {
  