tree_iterfrom
if (!tree_iterfrom(&evpcache_tree, &iter, evpid, &evpid, NULL))
if (tree_iterfrom(&ramqueue.messages, &i, from, &id, NULL) == 0)
if (tree_iterfrom(&msg->envelopes, &i, from, NULL,
int tree_iterfrom(struct tree *, void **, uint64_t, uint64_t *, void **);