code: def _delete_node_storage(self, node, is_root=False):
          
          if node == BLANK_NODE:
              return
          # assert isinstance(node, list)
          encoded = rlp_encode(node)
          if len(encoded) < 32 and not is_root:
              return
          """
          ===== FIXME ====
          in the current trie implementation two nodes can share identical subtrees
          thus we can not safely delete nodes for now
          """
          hashkey = utils.sha3(encoded)
          self.db.dec_refcount(hashkey)
docs: delete storage
          :param node: node in form of list, or BLANK_NODE