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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 dist_dir(self):
        '''The dist dir at which to place the finished distribution.'''
        if self.distribution is None:
            warning('Tried to access {}.dist_dir, but {}.distribution '
                    'is None'.format(self, self))
            exit(1)
        return self.distribution.dist_dir