anchor.diff:  
       if (emittedCode != null) {
         FunctionSignature signature = element.functionSignature;
  +      returnType = signature.type.returnType.toString();
         signature.forEachParameter((parameter) {
           parameters.add({
             'name': parameter.name,
  
positive.code:       'children': children,
        'size': size,
        'returnType': returnType,
        'parameters': parameters,
        'sideEffects': sideEffects,
        'code': code,
  
negative.code:     String kind = "function";
      List<String> children = [];
      List<Map<String, dynamic>> parameters = [];
      String inferredReturnType = null;
      String returnType = null;
      String sideEffects = null;
      String code = "";
  