anchor.diff:      buffer = null;
       index = 0;
     }
  +
  +  String get _partialResult => null;
   
     void writeNumber(num number) {
       writeAsciiString(number.toString());
  
positive.code:  * serializable, the [cause] is null.
   */
  class JsonUnsupportedObjectError extends Error {
    /** The object that could not be serialized. */
    final unsupportedObject;
    /** The exception thrown when trying to convert the object. */
    final cause;
  
    JsonUnsupportedObjectError(this.unsupportedObject, {this.cause});
  
    String toString() {
      if (cause != null) {
        return "Converting object to an encodable object failed.";
      } else {
        return "Converting object did not return an encodable object.";
      }
    }
  }
  
  
negative.code: 
    _JsonStringifier(toEncodable(o))
        : _toEncodable = toEncodable ?? _defaultToEncodable;
  
    String get _partialResult;
  
    /** Append a string to the JSON output. */
    void writeString(String characters);
  