support multiple keys for pfcount call

redis/client.py

@@ -1813,12 +1813,12 @@ def pfadd(self, name, *values):
         "Adds the specified elements to the specified HyperLogLog."
         return self.execute_command('PFADD', name, *values)
 
-    def pfcount(self, name):
+    def pfcount(self, *sources):
         """
         Return the approximated cardinality of
-        the set observed by the HyperLogLog at key.
+        the set observed by the HyperLogLog at key(s).
         """
-        return self.execute_command('PFCOUNT', name)
+        return self.execute_command('PFCOUNT', *sources)
 
     def pfmerge(self, dest, *sources):
         "Merge N different HyperLogLogs into a single one."

tests/test_commands.py

@@ -1106,6 +1106,10 @@ def test_pfcount(self, r):
         members = set([b('1'), b('2'), b('3')])
         r.pfadd('a', *members)
         assert r.pfcount('a') == len(members)
+        members_b = set([b('2'), b('3'), b('4')])
+        r.pfadd('b', *members_b)
+        assert r.pfcount('b') == len(members_b)
+        assert r.pfcount('a', 'b') == len(members_b.union(members))
 
     @skip_if_server_version_lt('2.8.9')
     def test_pfmerge(self, r):