more __all__ updates
diff --git a/Lib/doctest.py b/Lib/doctest.py
index 1b06990..887833e 100644
--- a/Lib/doctest.py
+++ b/Lib/doctest.py
@@ -371,6 +371,8 @@
 _isComment = re.compile(r"\s*#").match
 del re
 
+__all__ = []
+
 # Extract interactive examples from a string.  Return a list of triples,
 # (source, outcome, lineno).  "source" is the source code, and ends
 # with a newline iff the source spans more than one line.  "outcome" is