code: def from_json(self, filename: str, silent: bool=False) -> None:
          
          file_path = self.root_path / filename
          try:
              with open(file_path) as file_:
                  data = json.loads(file_.read())
          except (FileNotFoundError, IsADirectoryError):
              if not silent:
                  raise
          else:
              self.from_mapping(data)
docs: Load the configuration values from a JSON formatted file.
  
          This allows configuration to be loaded as so
  
          .. code-block:: python
  
              app.config.from_json('config.json')
  
          Arguments:
              filename: The filename which when appended to
                  :attr:`root_path` gives the path to the file.
              silent: If True any errors will fail silently.