--- a/pvl/rrd/args.py	Tue Feb 19 21:23:40 2013 +0200
+++ b/pvl/rrd/args.py	Tue Feb 19 21:28:57 2013 +0200
@@ -3,6 +3,9 @@
 import pvl.rrd.graph # interface
 from pvl.rrd import RRDDatabase, RRDCache
 
+import logging; log = logging.getLogger('pvl.rrd.args')
+import sys
+
 def parser (parser) :
     """
         optparse OptionGroup.