code: def get_sitej(self, site_index, image_index):
          
          atoms_n_occu = self.s[site_index].species
          lattice = self.s.lattice
          coords = self.s[site_index].frac_coords + self.offsets[image_index]
          return PeriodicSite(atoms_n_occu, coords, lattice)
docs: Assuming there is some value in the connectivity array at indices
          (1, 3, 12). sitei can be obtained directly from the input structure
          (structure[1]). sitej can be obtained by passing 3, 12 to this function
  
          Args:
              site_index (int): index of the site (3 in the example)
              image_index (int): index of the image (12 in the example)