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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def get_object(cls, abbr):
        '''
        This particular model needs its own constructor in order to take
        advantage of the metadata cache in billy.util, which would otherwise
        return unwrapped objects.
        '''
        obj = get_metadata(abbr)
        if obj is None:
            msg = 'No metadata found for abbreviation %r' % abbr
            raise DoesNotExist(msg)
        return cls(obj)