Take Tim's advice and have random.sample() support only sequences and sets.
diff --git a/Doc/library/random.rst b/Doc/library/random.rst
index ff5fb77..f08192d 100644
--- a/Doc/library/random.rst
+++ b/Doc/library/random.rst
@@ -111,8 +111,8 @@
.. function:: sample(population, k)
- Return a *k* length list of unique elements chosen from the population sequence.
- Used for random sampling without replacement.
+ Return a *k* length list of unique elements chosen from the population sequence
+ or set. Used for random sampling without replacement.
Returns a new list containing elements from the population while leaving the
original population unchanged. The resulting list is in selection order so that