move import into function to avoid having to add an __all__ list...

Lib/whichdb.py

 """Guess which db package to use to open a db file."""
 
-import struct
-
 def whichdb(filename):
     """Guess which db package to use to open a db file.
 
@@ -15,6 +13,8 @@ def whichdb(filename):
     database using that module may still fail.
     """
 
+    import struct
+
     # Check for dbm first -- this has a .pag and a .dir file
     try:
         f = open(filename + ".pag", "rb")