anchor.diff:      return false;
     }
   
  -  /**
  -   * Push the operation for the given assignable [expr].
  -   */
  +  /// Push the operation for the given assignable [expr].
     void _pushAssignable(Expression expr) {
       if (_isIdentifierSequence(expr)) {
         EntityRefBuilder ref = serializeIdentifierSequence(expr);
  
positive.code:         references: references);
    }
  
    /**
     * Return `true` if the given [expr] is a sequence of identifiers.
     */
    bool _isIdentifierSequence(Expression expr) {
      while (expr != null) {
        if (expr is SimpleIdentifier) {
  
negative.code:         'Cannot serialize an instance of ${type.runtimeType}');
    }
  
    /// Return [EntityRefBuilder] that corresponds to the type with the given
    /// [name] and [arguments].
    EntityRefBuilder serializeTypeName(
        Identifier name, TypeArgumentList arguments);
  
    /// Return the [UnlinkedExprBuilder] that corresponds to the state of this
    /// serializer.
    UnlinkedExprBuilder toBuilder() {
      return new UnlinkedExprBuilder(
          isValidConst: isValidConst,
  