code: def convex_conj(self):
          
          if self.exponent == np.inf:
              return L1Norm(self.domain)
          elif self.exponent == 2:
              return L2Norm(self.domain)
          else:
              return LpNorm(self.domain, exponent=conj_exponent(self.exponent))
docs: The conjugate functional of IndicatorLpUnitBall.
  
          The convex conjugate functional of an ``Lp`` norm, ``p < infty`` is the
          indicator function on the unit ball defined by the corresponding dual
          norm ``q``, given by ``1/p + 1/q = 1`` and where ``q = infty`` if
          ``p = 1`` [Roc1970]. By the Fenchel-Moreau theorem, the convex
          conjugate functional of indicator function on the unit ball in ``Lq``
          is the corresponding Lp-norm [BC2011].
  
          References
          ----------
          [Roc1970] Rockafellar, R. T. *Convex analysis*. Princeton
          University Press, 1970.
  
          [BC2011] Bauschke, H H, and Combettes, P L. *Convex analysis and
          monotone operator theory in Hilbert spaces*. Springer, 2011.