How to use the cssselect.ExpressionError function in cssselect

selector, = parse('e:after')
        assert selector.pseudo_element == 'after'
        # Pseudo-element is ignored:
        assert GenericTranslator().selector_to_xpath(selector, prefix='') == "e"

        # Invalid characters in XPath element names
        assert xpath(r'di\a0 v') == (
            u("*[name() = 'di v']"))  # di\xa0v
        assert xpath(r'di\[v') == (
            "*[name() = 'di[v']")
        assert xpath(r'[h\a0 ref]') == (
            u("*[attribute::*[name() = 'h ref']]"))  # h\xa0ref
        assert xpath(r'[h\]ref]') == (
            "*[attribute::*[name() = 'h]ref']]")

        self.assertRaises(ExpressionError, xpath, u(':fİrst-child'))
        self.assertRaises(ExpressionError, xpath, ':first-of-type')
        self.assertRaises(ExpressionError, xpath, ':only-of-type')
        self.assertRaises(ExpressionError, xpath, ':last-of-type')
        self.assertRaises(ExpressionError, xpath, ':nth-of-type(1)')
        self.assertRaises(ExpressionError, xpath, ':nth-last-of-type(1)')
        self.assertRaises(ExpressionError, xpath, ':nth-child(n-)')
        self.assertRaises(ExpressionError, xpath, ':after')
        self.assertRaises(ExpressionError, xpath, ':lorem-ipsum')
        self.assertRaises(ExpressionError, xpath, ':lorem(ipsum)')
        self.assertRaises(ExpressionError, xpath, '::lorem-ipsum')
        self.assertRaises(TypeError, GenericTranslator().css_to_xpath, 4)
        self.assertRaises(TypeError, GenericTranslator().selector_to_xpath,
            'foo')

# Invalid characters in XPath element names
        assert xpath(r'di\a0 v') == (
            u("*[name() = 'di v']"))  # di\xa0v
        assert xpath(r'di\[v') == (
            "*[name() = 'di[v']")
        assert xpath(r'[h\a0 ref]') == (
            u("*[attribute::*[name() = 'h ref']]"))  # h\xa0ref
        assert xpath(r'[h\]ref]') == (
            "*[attribute::*[name() = 'h]ref']]")

        self.assertRaises(ExpressionError, xpath, u(':fİrst-child'))
        self.assertRaises(ExpressionError, xpath, ':first-of-type')
        self.assertRaises(ExpressionError, xpath, ':only-of-type')
        self.assertRaises(ExpressionError, xpath, ':last-of-type')
        self.assertRaises(ExpressionError, xpath, ':nth-of-type(1)')
        self.assertRaises(ExpressionError, xpath, ':nth-last-of-type(1)')
        self.assertRaises(ExpressionError, xpath, ':nth-child(n-)')
        self.assertRaises(ExpressionError, xpath, ':after')
        self.assertRaises(ExpressionError, xpath, ':lorem-ipsum')
        self.assertRaises(ExpressionError, xpath, ':lorem(ipsum)')
        self.assertRaises(ExpressionError, xpath, '::lorem-ipsum')
        self.assertRaises(TypeError, GenericTranslator().css_to_xpath, 4)
        self.assertRaises(TypeError, GenericTranslator().selector_to_xpath,
            'foo')

assert xpath('e ~ f') == (
            "e/following-sibling::f")
        assert xpath('div#container p') == (
            "div[@id = 'container']/descendant-or-self::*/p")

        # Invalid characters in XPath element names
        assert xpath(r'di\a0 v') == (
            u("*[name() = 'di v']"))  # di\xa0v
        assert xpath(r'di\[v') == (
            "*[name() = 'di[v']")
        assert xpath(r'[h\a0 ref]') == (
            u("*[attribute::*[name() = 'h ref']]"))  # h\xa0ref
        assert xpath(r'[h\]ref]') == (
            "*[attribute::*[name() = 'h]ref']]")

        self.assertRaises(ExpressionError, xpath, ':first-of-type')
        self.assertRaises(ExpressionError, xpath, ':only-of-type')
        self.assertRaises(ExpressionError, xpath, ':last-of-type')
        self.assertRaises(ExpressionError, xpath, ':nth-of-type(1)')
        self.assertRaises(ExpressionError, xpath, ':nth-last-of-type(1)')
        self.assertRaises(ExpressionError, xpath, ':nth-child(n-)')
        self.assertRaises(ExpressionError, xpath, ':after')
        self.assertRaises(ExpressionError, xpath, ':lorem-ipsum')
        self.assertRaises(ExpressionError, xpath, ':lorem(ipsum)')
        self.assertRaises(ExpressionError, xpath, '::lorem-ipsum')
        self.assertRaises(TypeError, GenericTranslator().css_to_xpath, 4)
        self.assertRaises(TypeError, GenericTranslator().selector_to_xpath,
            'foo')

assert xpath(r'di\[v') == (
            "*[name() = 'di[v']")
        assert xpath(r'[h\a0 ref]') == (
            u("*[attribute::*[name() = 'h ref']]"))  # h\xa0ref
        assert xpath(r'[h\]ref]') == (
            "*[attribute::*[name() = 'h]ref']]")

        self.assertRaises(ExpressionError, xpath, ':first-of-type')
        self.assertRaises(ExpressionError, xpath, ':only-of-type')
        self.assertRaises(ExpressionError, xpath, ':last-of-type')
        self.assertRaises(ExpressionError, xpath, ':nth-of-type(1)')
        self.assertRaises(ExpressionError, xpath, ':nth-last-of-type(1)')
        self.assertRaises(ExpressionError, xpath, ':nth-child(n-)')
        self.assertRaises(ExpressionError, xpath, ':after')
        self.assertRaises(ExpressionError, xpath, ':lorem-ipsum')
        self.assertRaises(ExpressionError, xpath, ':lorem(ipsum)')
        self.assertRaises(ExpressionError, xpath, '::lorem-ipsum')
        self.assertRaises(TypeError, GenericTranslator().css_to_xpath, 4)
        self.assertRaises(TypeError, GenericTranslator().selector_to_xpath,
            'foo')

def xpath_pseudo_element(self, xpath, pseudo_element):
                if isinstance(pseudo_element, FunctionalPseudoElement):
                    method = 'xpath_%s_functional_pseudo_element' % (
                        pseudo_element.name.replace('-', '_'))
                    method = _unicode_safe_getattr(self, method, None)
                    if not method:
                        raise ExpressionError(
                            "The functional pseudo-element ::%s() is unknown"
                        % pseudo_element.name)
                    xpath = method(xpath, pseudo_element.arguments)
                else:
                    method = 'xpath_%s_simple_pseudo_element' % (
                        pseudo_element.replace('-', '_'))
                    method = _unicode_safe_getattr(self, method, None)
                    if not method:
                        raise ExpressionError(
                            "The pseudo-element ::%s is unknown"
                            % pseudo_element)
                    xpath = method(xpath)
                return xpath

for rule in stylesheet.cssRules:
                rules.extend(self.flatten_rule(rule, href, index))
                index = index + 1
        # XXX had to fix crash about unsortable type, so that's why we only sort by first item of tuple
        rules.sort(key=lambda tup: tup[:1])
        self.rules = rules
        self._styles = {}
        class_sel_pat = re.compile(r'\.[a-z]+', re.IGNORECASE)
        capital_sel_pat = re.compile(r'h|[A-Z]+')
        for _, _, cssdict, text, _ in rules:
            fl = ':first-letter' in text
            if fl:
                text = text.replace(':first-letter', '')
            try:
                selector = CSSSelector(text)
            except (AssertionError, ExpressionError, etree.XPathSyntaxError,
                    NameError, # thrown on OS X instead of SelectorSyntaxError
                    SelectorSyntaxError):
                continue
            try:
                matches = selector(tree)
            except etree.XPathEvalError:
                continue

            if not matches:
                ntext = capital_sel_pat.sub(lambda m: m.group().lower(), text)
                if ntext != text:
                    logging.warn('Transformed CSS selector' + text + 'to' + ntext)
                    selector = CSSSelector(ntext)
                    matches = selector(tree)

            if not matches and class_sel_pat.match(text) and text.lower() != text: