code: def apply_transformation(self, structure):
          
          if structure != self.defect.bulk_structure:
              raise ValueError("Defect bulk_structure is not the same as input structure.")
  
          def_structure = self.defect.generate_defect_structure(self.scaling_matrix)
  
          return def_structure
docs: :param structure (bulk structure to be scaled up - typically conventional unit cell)
          :return:
              defect_structure, with charge applied