def register(self, name=None, **kwargs):
        """Register a format.

        Parameters
        ----------

        reader : class
            A class that implements read(contents) which yield ipymd cells.
        writer : class
            A class that implements write(cell) and contents.
        file_extension : str
            The file extension with the leading dot, like '.md'
        file_type : 'text' or 'json'
            The type of the file format.
        load : function
            a custom `contents = load(path)` function if no file type
               is specified.
        save : function
            a custom `save(path, contents)` function if no file type
               is specified.

        """
        assert name is not None
        self._formats[name] = kwargs
Register a format.

        Parameters
        ----------

        reader : class
            A class that implements read(contents) which yield ipymd cells.
        writer : class
            A class that implements write(cell) and contents.
        file_extension : str
            The file extension with the leading dot, like '.md'
        file_type : 'text' or 'json'
            The type of the file format.
        load : function
            a custom `contents = load(path)` function if no file type
               is specified.
        save : function
            a custom `save(path, contents)` function if no file type
               is specified.

        
ipymd/core/format_manager.py