def get_validator_change(cls, bigchain):
        """Return the validator set from the most recent approved block

        :return: {
            'height': <block_height>,
            'validators': <validator_set>
        }
        """
        latest_block = bigchain.get_latest_block()
        if latest_block is None:
            return None
        return bigchain.get_validator_change(latest_block['height'])
Return the validator set from the most recent approved block

        :return: {
            'height': <block_height>,
            'validators': <validator_set>
        }