def _filter_xpath_grouping(xpath):
    """
    This method removes the outer parentheses for xpath grouping.
    The xpath converter will break otherwise.
    Example:
    "(//button[@type='submit'])[1]" becomes "//button[@type='submit'][1]"
    """

    # First remove the first open parentheses
    xpath = xpath[1:]

    # Next remove the last closed parentheses
    index = xpath.rfind(')')
    if index == -1:
        raise XpathException("Invalid or unsupported Xpath: %s" % xpath)
    xpath = xpath[:index] + xpath[index + 1:]
    return xpath