def convert_pandoc_rst(source, from_format, to_format, extra_args=None):
    """
    Overwrites `convert_pandoc
    <https://github.com/jupyter/nbconvert/blob/master/nbconvert/filters/pandoc.py>`_.

    @param      source          string to convert
    @param      from_format     from format
    @param      to_format       to format
    @param      extra_args      extra arguments
    @return                     results
    """
    return convert_pandoc(source, from_format, to_format, extra_args=None)