Move old style exception to new style exceptions as old style exceptions are deprecated in Python 2 and removed from Python 3 because they are ambiguous.
Move old style exception to new style exceptions as old style exceptions are deprecated in Python 2 and removed from Python 3 because they are ambiguous.

Addresses pull request https://github.com/google/deepvariant/pull/4 from cclauss@.

PiperOrigin-RevId: 178036187

google/deepvariant,google/deepvariant,google/deepvariant