code: def full_y(self, Y):
          
          if not self.n:
              return
          Ysh = matrix(self.g,
                       (self.n, 1), 'd') + 1j * matrix(self.b, (self.n, 1), 'd')
          uYsh = mul(self.u, Ysh)
          Y += spmatrix(uYsh, self.a, self.a, Y.size, 'z')
docs: Add self(shunt) into full Jacobian Y