+ /**
+ * @brief Get a valid pointer to a value corresponding to a given key
+ *
+ * Ensure that key is present in the hash table, then return a pointer
+ * to its value bin. This may require either creating a new bin for
+ * this key (with a default-constructed value) or simply locating and
+ * returning a pointer to an existing value.
+ * @param key The key to check
+ * @return A pointer to the value in the table
+ */
+ _Val * get_safe_ptr(_Key key) {