code: def _stringify(self, data):
          
          if isinstance(data, string_types):
              return data
  
          # Get the most compact dictionary (separators) and sort the keys recursively to get a stable output
          return json.dumps(data, separators=(',', ':'), sort_keys=True)
docs: Stable, platform & language-independent stringification of a data with basic Python type.
  
          We use JSON to dump a string instead of `str()` method in order to be language independent.
  
          :param data: Data to be stringified. If this is one of JSON native types like string, dict, array etc, it will
                       be properly serialized. Otherwise this method will throw a TypeError for non-JSON serializable
                       objects
          :return: string representation of the dictionary
          :rtype string