implement 'util.unique_squence()'

gallery_dl/util.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 
-# Copyright 2017-2020 Mike Fährmann
+# Copyright 2017-2021 Mike Fährmann
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 2 as
@@ -65,6 +65,15 @@ def unique(iterable):
             yield element
 
 
+def unique_sequence(iterable):
+    """Yield sequentially unique elements from 'iterable'"""
+    last = None
+    for element in iterable:
+        if element != last:
+            last = element
+            yield element
+
+
 def raises(cls):
     """Returns a function that raises 'cls' as exception"""
     def wrap(*args):