anchor.diff:  
     ClassBlock(this.name, this.args, this.extension, this.block);
   
  -
  +  String get className => name.name;
   }
   
   class TryCatchStatement extends Statement {
  
positive.code:   final Expression expression;
  
    ExpressionStatement(this.expression);
  }
  
  class MethodCall extends Expression {
  
negative.code:   final List<Expression> args;
  
    MethodCall(this.reference, this.args);
    MethodCall.withNoArguments(this.reference) : args = [];
  
    @override
    String toString() => "MethodCall(reference: ${reference}, args: ${args})";
  