convert detailed proxy info into a dict

        Returns:
            dict: A dict with four keys: ``addr``, ``protocol``,
                  ``weight`` and ``last_checked``

def to_dict(self):
        """convert detailed proxy info into a dict

        Returns:
            dict: A dict with four keys: ``addr``, ``protocol``,
                  ``weight`` and ``last_checked``
        """
        return dict(
            addr=self.addr,
            protocol=self.protocol,
            weight=self.weight,
            last_checked=self.last_checked)