def codemirror_html(self, config_name, varname, element_id):
        """
        Render HTML for a CodeMirror instance.

        Since a CodeMirror instance have to be attached to a HTML element, this
        method requires a HTML element identifier with or without the ``#``
        prefix, it depends from template in
        ``settings.CODEMIRROR_FIELD_INIT_JS`` (default one require to not
        prefix with ``#``).

        Arguments:
            config_name (string): A registred config name.
            varname (string): A Javascript variable name.
            element_id (string): An HTML element identifier (without
                leading ``#``) to attach to a CodeMirror instance.

        Returns:
            string: HTML to instanciate CodeMirror for a field input.
        """
        parameters = json.dumps(self.get_codemirror_parameters(config_name),
                                sort_keys=True)
        return settings.CODEMIRROR_FIELD_INIT_JS.format(
            varname=varname,
            inputid=element_id,
            settings=parameters,
        )
Render HTML for a CodeMirror instance.

        Since a CodeMirror instance have to be attached to a HTML element, this
        method requires a HTML element identifier with or without the ``#``
        prefix, it depends from template in
        ``settings.CODEMIRROR_FIELD_INIT_JS`` (default one require to not
        prefix with ``#``).

        Arguments:
            config_name (string): A registred config name.
            varname (string): A Javascript variable name.
            element_id (string): An HTML element identifier (without
                leading ``#``) to attach to a CodeMirror instance.

        Returns:
            string: HTML to instanciate CodeMirror for a field input.