code: def i_ll(self):
          
          d_values = []
          for i in range(self.n_pads_w):
              d_values.append(self.pad_position_w(i))
          d_values = np.array(d_values) - self.width / 2
          area_d_sqrd = sum(self.pad_area * d_values ** 2) * self.n_pads_l
          i_second = self.pad_i_ll * self.n_pads
          return area_d_sqrd + i_second
docs: Second moment of inertia around the length axis.
          :return: