Change all the function attributes from func_* -> __*__.  This gets rid
of func_name, func_dict and func_doc as they already exist as __name__,
__dict__ and __doc__.
diff --git a/Lib/trace.py b/Lib/trace.py
index a1f9ade..79d2171 100644
--- a/Lib/trace.py
+++ b/Lib/trace.py
@@ -532,7 +532,7 @@
             ## use of gc.get_referrers() was suggested by Michael Hudson
             # all functions which refer to this code object
             funcs = [f for f in gc.get_referrers(code)
-                         if hasattr(f, "func_doc")]
+                         if hasattr(f, "__doc__")]
             # require len(func) == 1 to avoid ambiguity caused by calls to
             # new.function(): "In the face of ambiguity, refuse the
             # temptation to guess."