Update filter_unique.md

snippets/filter_unique.md

@@ -5,13 +5,13 @@ tags: list,beginner
 
 Filters out the unique values in a list.
 
-Use list comprehension and `list.count()` to create a list containing only the unique values.
+Use list comprehension and `list.count()` to create a list containing only the non-unique values.
 
 ```py
 def filter_unique(lst):
-  return [item for item in lst if lst.count(item) == 1]
+  return [x for x in set(item for item in lst if lst.count(item) > 1)]
 ```
 
 ```py
-filter_unique([1, 2, 2, 3, 4, 4, 5]) # [1, 3, 5]
-```
+filter_unique([1, 2, 2, 3, 4, 4, 5]) # [2, 4]
+```