Counter: fix recipe for "n least common elements". Found by Mikhail Golubev on docs@.
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index a65fe5b..a47d99b 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -307,7 +307,7 @@
dict(c) # convert to a regular dictionary
c.items() # convert to a list of (elem, cnt) pairs
Counter(dict(list_of_pairs)) # convert from a list of (elem, cnt) pairs
- c.most_common()[:-n:-1] # n least common elements
+ c.most_common()[:-n-1:-1] # n least common elements
+c # remove zero and negative counts
Several mathematical operations are provided for combining :class:`Counter`