Update 07_dict.py

tests/07_dict.py

@@ -162,3 +162,11 @@ except TypeError:
 a = {1: 2, 3: 4}
 a['a'] = a
 assert repr(a) == "{1: 2, 3: 4, 'a': {...}}"
+
+# test gc
+import gc
+gc.collect()
+x = gc.collect()
+for k, v in a.items():
+    pass
+assert x+1 == gc.collect()