'For when you have the tag and you want to know where it is.'

def testFindByIndex(self):

    tag = self.soup.find('a', id='a')
    self.assertEqual(self.soup.index(tag), 3)
    s = tag.string
    self.assertEqual(tag.index(s), 0)
    soup2 = BeautifulSoup('<b></b>')
    tag2 = soup2.find('b')
    self.assertRaises(ValueError, self.soup.index, tag2)
