+/**
+ * dgraph_check - check a graph for consistency
+ * @n: the dgraph_node to check.
+ * @abortstr: the string to print on aborting, or NULL.
+ *
+ * Returns @n if the list is consistent, NULL if not (it can never
+ * return NULL if @abortstr is set).
+ *
+ * See also: tlist_check()
+ */
+struct dgraph_node *dgraph_check(const struct dgraph_node *n,
+ const char *abortstr);