uu_avl_walk
(void) uu_avl_walk(lines, print_line, NULL, 0);
typedef struct uu_avl_walk uu_avl_walk_t;
int uu_avl_walk(uu_avl_t *, uu_walk_fn_t *, void *, uint32_t);
(void) uu_avl_walk(mgr_ctx->mc_svcs, svcctl_scm_cb_bytes_needed,