Validating Command Line Options

[T]

For a Python script with multiple command line options, what is the
best way to go about validating that only certain options are used
together?  For example, say -s, -t, and -v are all valid options, but
should never be used together (i.e. -s -t would be invalid).  Thanks
in advance.
-- 
http://mail.python.org/mailman/listinfo/python-list