--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/pyams_utils/list.py	Thu Feb 19 00:46:48 2015 +0100
@@ -0,0 +1,41 @@
+#
+# Copyright (c) 2008-2015 Thierry Florac <tflorac AT ulthar.net>
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+
+__docformat__ = 'restructuredtext'
+
+
+# import standard library
+
+# import interfaces
+
+# import packages
+
+
+def unique(seq, idfun=None):
+    """Extract unique values from list, preserving order
+
+    >>> from pyams_utils.list import unique
+    >>> mylist = [1, 2, 3, 2, 1]
+    >>> unique(mylist)
+    [1, 2, 3]
+    """
+    if idfun is None:
+        def idfun(x): return x
+    seen = {}
+    result = []
+    for item in seq:
+        marker = idfun(item)
+        if marker in seen:
+            continue
+        seen[marker] = 1
+        result.append(item)
+    return result