Return the alert status relative to the web/url scan return value.

def get_web_alert(self, web, header="", log=False):
        """Return the alert status relative to the web/url scan return value."""
        ret = 'OK'
        if web['status'] is None:
            ret = 'CAREFUL'
        elif web['status'] not in [200, 301, 302]:
            ret = 'CRITICAL'
        elif web['rtt_warning'] is not None and web['elapsed'] > web['rtt_warning']:
            ret = 'WARNING'

        # Get stat name
        stat_name = self.get_stat_name(header=header)

        # Manage threshold
        self.manage_threshold(stat_name, ret)

        # Manage action
        self.manage_action(stat_name,
                           ret.lower(),
                           header,
                           web[self.get_key()])

        return ret