code: def _call(self, x):
          
          if isinstance(self.domain, ProductSpace):
              norm = PointwiseNorm(self.domain, 2)(x)
          else:
              norm = x.ufuncs.absolute()
  
          if self.gamma > 0:
              tmp = norm.ufuncs.square()
              tmp *= 1 / (2 * self.gamma)
  
              index = norm.ufuncs.greater_equal(self.gamma)
              tmp[index] = norm[index] - self.gamma / 2
          else:
              tmp = norm
  
          return tmp.inner(tmp.space.one())
docs: Return ``self(x)``.