Expanded tests for sets of sets.
diff --git a/Lib/test/test_sets.py b/Lib/test/test_sets.py
index a2aa69a..b56219b 100644
--- a/Lib/test/test_sets.py
+++ b/Lib/test/test_sets.py
@@ -138,6 +138,10 @@
outer = Set([inner])
element = outer.pop()
assert type(element) == ImmutableSet, "Construct set of sets"
+ outer.add(inner) # Rebuild set of sets with .add method
+ outer.remove(inner)
+ assert outer == Set() # Verify that remove worked
+ outer.discard(inner) # Absence of KeyError indicates working fine
#==============================================================================