code: def proximal(self):
          
          if self.exponent == 1:
              return proximal_l1(space=self.domain)
          elif self.exponent == 2:
              return proximal_l2(space=self.domain)
          elif self.exponent == np.inf:
              return proximal_linfty(space=self.domain)
          else:
              raise NotImplementedError('`proximal` only implemented for p=1, '
                                        'p=2, and p=inf')
docs: Return the proximal factory of the functional.
  
          See Also
          --------
          odl.solvers.nonsmooth.proximal_operators.proximal_l1 :
              proximal factory for the L1-norm.
          odl.solvers.nonsmooth.proximal_operators.proximal_l2 :
              proximal factory for the L2-norm.