code: def ystep(self):
          r
  
          self.Y = np.asarray(sp.proj_l1(self.AX + self.U, self.gamma, axis=0),
                              dtype=self.dtype)
          super(BPDNProjL1, self).ystep()
docs: r"""Minimise Augmented Lagrangian with respect to
          :math:`\mathbf{y}`.