def remove_node(self, node: StorageNode) -> int:

    """remove_node removes the node and returns the key

    from the hash space on which the node was placed.

    """

​

    # handling error when space is empty

    if len(self._keys) == 0:

        raise Exception("hash space is empty")

​

    key = hash_fn(node.host, self.total_slots)

​

    # we find the index where the key would reside in the keys

    index = bisect_left(self._keys, key)

​

    # if key does not exist in the array we raise Exception

    if index >= len(self._keys) or self._keys[index] != key:

        raise Exception("node does not exist")

​

    # Perform data migration

​

    # now that all sanity checks are done we popping the

    # keys and nodes at the index and thus removing the presence of the node.

    self._keys.pop(index)

    self.nodes.pop(index)

​

    return key