code: def _make_interpolation(self):
          
          H0_range = np.linspace(10, 100, 90)
          omega_m_range = np.linspace(0.05, 1, 95)
          grid2d = np.dstack(np.meshgrid(H0_range, omega_m_range)).reshape(-1, 2)
          H0_grid = grid2d[:, 0]
          omega_m_grid = grid2d[:, 1]
          Dd_grid = np.zeros_like(H0_grid)
          Ds_Dds_grid = np.zeros_like(H0_grid)
          for i in range(len(H0_grid)):
              Dd, Ds_Dds = self.cosmo2Dd_Ds_Dds(H0_grid[i], omega_m_grid[i])
              Dd_grid[i] = Dd
              Ds_Dds_grid[i] = Ds_Dds
          self._f_H0 = interpolate.interp2d(Dd_grid, Ds_Dds_grid, H0_grid, kind='linear', copy=False, bounds_error=False, fill_value=-1)
          print("H0 interpolation done")
          self._f_omega_m = interpolate.interp2d(Dd_grid, Ds_Dds_grid, omega_m_grid, kind='linear', copy=False, bounds_error=False, fill_value=-1)
          print("omega_m interpolation done")
docs: creates an interpolation grid in H_0, omega_m and computes quantities in Dd and Ds_Dds
          :return: