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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 adjoint(self):
 """Adjoint of this operator, a `SamplingOperator`. The ``'char_fun'`` variant of this operator corresponds to the ``'integrate'`` sampling operator, and ``'dirac'`` corresponds to ``'point_eval'``. Examples -------- rn(4).element([ 1., 5., 6., 1.]) True True """

        if self.variant == 'dirac':
            variant = 'point_eval'
        elif self.variant == 'char_fun':
            variant = 'integrate'
        else:
            raise RuntimeError('The variant "{!r}" is not yet supported'
                               ''.format(self.variant))

        return SamplingOperator(self.range, self.sampling_points, variant)