I don't understand how to use the testing framework.  I did this:

```diff
diff --git a/test/completion/docstring.py b/test/completion/docstring.py
index 66b6744..1cd1d25 100644
--- a/test/completion/docstring.py
+++ b/test/completion/docstring.py
@@ -1,10 +1,11 @@
 """ Test docstrings in functions and classes, which are used to infer types """
 
-def f(a, b):
+def f(a, b, c):
     """ asdfasdf
     :param a: blablabla
     :type a: str
     :type b: (str, int)
+    :type c: threading.Thread
     :rtype: dict
     """
     #? str()
@@ -13,6 +14,8 @@ def f(a, b):
     b[0]
     #? int()
     b[1]
+    #? threading.Thread()
+    c
 
 #? dict()
 f()
```

But I've got:

```
Traceback (most recent call last):
  File "run.py", line 180, in run_test
    should_str = get_defs(correct, start, path)
  File "run.py", line 149, in get_defs
    % (line_nr - 1, should_str))
Exception: Solution @17 not right, too few test results: set([])

test @17:     c

run 14 tests with 1 fails (docstring.py)
```