Fix typo in return value from README (fixes #652)

The same code is in both the README and compliant03.py. This change fixes the typo in compliant03.py.

Signed-off-by: Michael Scovetta <[email protected]>

Author: scovetta

docs/Secure-Coding-Guide-for-Python/CWE-703/CWE-392/compliant03.py

@@ -19,7 +19,7 @@ def map_threads(x):
             for res in result_gen:
                 ret.append(res)
                 invalid_arg += 1
-            return res
+            return ret
         except ValueError as e:
             # handle exception...
             raise ValueError(