title: how to stringify json in flutter
body: <p>In flutter(dart), it is easy to deserialize <code>Json</code> and get a token from it, but when I try to serialize it again, the quotation marks around the keys and values with disappear.</p>
  
  <pre><code>String myJSON = '{"name":{"first":"foo","last":"bar"}, "age":31, "city":"New York"}';
  var json = JSON.jsonDecode(myJSON); //_InternalLinkedHashMap
  var nameJson = json['name']; //_InternalLinkedHashMap
  String nameString = nameJson.toString();
  </code></pre>
  
  <p>Although the <code>nameJson</code> have all the double quotations, the <code>nameString</code> is </p>
  
  <p><code>{first: foo, last: bar}</code></p>
  
  <p><em>(true answer is <code>{"first": "foo", "last": "bar"}</code>)</em></p>
  
  <p>how to preserve Dart to remove the <code>"</code>s?</p>