anchor.diff:            {int statusCode: HttpStatus.ok,
             Map<String, dynamic> headers,
             String mimeType: MimeTypes.json,
  -          String charset}) =>
  +          String charset: kDefaultCharset}) =>
         Response<String>(
           cnv.json.encode(value),
           statusCode: statusCode,
  
positive.code: import 'dart:io';
  import 'dart:convert' as cnv;
  import 'package:jaguar/http/http.dart';
  
  export 'byte_response.dart';
  export 'redirect_response.dart';
  
negative.code:       {this.statusCode: 200,
        Map<String, dynamic> headers,
        String mimeType,
        String charset: kDefaultCharset }) {
      if (headers != null)
        for (final String name in headers.keys) {
          this.headers.add(name, headers[name]);
  