def refresh(self):
        """ Even though blocks never change, you freshly obtain its contents
            from an API with this method
        """
        block = self.blockchain.rpc.get_block_header(self.identifier)
        if not block:
            raise BlockDoesNotExistsException
        super(BlockHeader, self).__init__(
            block, blockchain_instance=self.blockchain, use_cache=self._use_cache
        )
Even though blocks never change, you freshly obtain its contents
            from an API with this method