'Find code blocks and store in htmlStash.'

def run(self, root):

    blocks = root.iter(u'pre')
    for block in blocks:
        if ((len(block) == 1) and (block[0].tag == u'code')):
            html = highlight(block[0].text, self.config, self.markdown.tab_length)
            placeholder = self.markdown.htmlStash.store(html, safe=True)
            block.clear()
            block.tag = u'p'
            block.text = placeholder
