delete storage
        :param node: node in form of list, or BLANK_NODE

def _delete_node_storage(self, node):
        """delete storage
        :param node: node in form of list, or BLANK_NODE
        """
        if node == BLANK_NODE:
            return
        # assert isinstance(node, list)
        encoded = self._encode_node(node, put_in_db=False)
        if len(encoded) < 32:
            return
        """
        ===== FIXME ====
        in the current trie implementation two nodes can share identical subtrees
        thus we can not safely delete nodes for now
        """
        self.deletes.append(encoded)