Raises stored :class:`HTTPError`, if one occurred.

def raise_for_status(self):
        """Raises stored :class:`HTTPError`, if one occurred."""

        http_error_msg = ''
        if isinstance(self.reason, bytes):
            # We attempt to decode utf-8 first because some servers
            # choose to localize their reason strings. If the string
            # isn't utf-8, we fall back to iso-8859-1 for all other
            # encodings. (See PR #3538)
            try:
                reason = self.reason.decode('utf-8')
            except UnicodeDecodeError:
                reason = self.reason.decode('iso-8859-1')
        else:
            reason = self.reason

        if 400 <= self.status_code < 500:
            http_error_msg = u'%s Client Error: %s for url: %s' % (self.status_code, reason, self.url)

        elif 500 <= self.status_code < 600:
            http_error_msg = u'%s Server Error: %s for url: %s' % (self.status_code, reason, self.url)

        if http_error_msg:
            raise HTTPError(http_error_msg, response=self)