code: def from_json(self, filename, encoding='utf-8', silent=False):
          
          self.from_file(json.load, filename, encoding, silent)
docs: Updates recursively the value in the the config from a JSON file.
  
          :param filename: (str) a filename of the JSON file
          :param encoding: (str) an encoding of the filename
          :param silent: (bool) fails silently if something wrong with json file
  
          .. versionadded:: 0.3.0