diff -r bf3695fee719 -r 481802342fdf ucx/list.c
--- a/ucx/list.c	Mon Feb 04 14:11:57 2019 +0100
+++ b/ucx/list.c	Mon Feb 04 17:17:48 2019 +0100
@@ -77,6 +77,7 @@
 }
 
 void ucx_list_free_content(UcxList* list, ucx_destructor destr) {
+    if (!destr) destr = free;
     while (list != NULL) {
         destr(list->data);
         list = list->next;
@@ -106,41 +107,6 @@
     }
 }
 
-UcxList *ucx_list_append_once(UcxList *l, void *data,
-        cmp_func cmpfnc, void *cmpdata) {
-    return ucx_list_append_once_a(ucx_default_allocator(), l,
-            data, cmpfnc, cmpdata);
-}
-
-UcxList *ucx_list_append_once_a(UcxAllocator *alloc, UcxList *l, void *data,
-        cmp_func cmpfnc, void *cmpdata) {
-
-    UcxList *last = NULL;
-    {
-        UcxList *e = l;
-        while (e) {
-            if (cmpfnc(e->data, data, cmpdata) == 0) {
-                return l;
-            }
-            last = e;
-            e = e->next;
-        }
-    }
-    
-    UcxList *nl = ucx_list_append_a(alloc, NULL, data);
-    if (!nl) {
-        return NULL;
-    }
-
-    if (last == NULL) {
-        return nl;
-    } else {
-        nl->prev = last;
-        last->next = nl;
-        return l;
-    }
-}
-
 UcxList *ucx_list_prepend(UcxList *l, void *data) {
     return ucx_list_prepend_a(ucx_default_allocator(), l, data);
 }