code: def serialize_dictionary(dictionary):
      
      string_value = {}
      for k, v in list(dictionary.items()):
          if isinstance(v, QUrl):
              string_value[k] = v.toString()
          elif isinstance(v, (QDate, QDateTime)):
              string_value[k] = v.toString(Qt.ISODate)
          elif isinstance(v, datetime):
              string_value[k] = v.isoformat()
          elif isinstance(v, date):
              string_value[k] = v.isoformat()
          elif isinstance(v, dict):
              # Recursive call
              string_value[k] = serialize_dictionary(v)
          else:
              string_value[k] = v
      return string_value
docs: Function to stringify a dictionary recursively.
  
      :param dictionary: The dictionary.
      :type dictionary: dict
  
      :return: The string.
      :rtype: basestring