refactor, load_deleted - needs to be tested

airflow/dags/grades/grades_increment.py

airflow/dags/grades/grades_source_to_stage.py

airflow/dags/grades/grades_stage_to_target.py

airflow/dags/grades/testing/concat_np.py

airflow/dags/grades/testing/cursor.py

airflow/dags/grades/testing/grades_to_ps.py

airflow/dags/grades/testing/load_t_klas_klasifikace.py

.../grades/testing/stage_to_target_grades_klasifikace (1).py

...dags/grades/testing/stage_to_target_grades_klasifikace.py

airflow/dags/grades/testing/test_stage.py

airflow/dags/helpers/__init__.py

airflow/dags/helpers/connections.py

airflow/dags/helpers/dwh_email.py

airflow/dags/helpers/increment.py

airflow/dags/helpers/increment_no_psc.py

airflow/dags/helpers/stage_functions.py

airflow/dags/helpers/stage_functions_no_psc.py

airflow/dags/helpers/stringiteratorio.py

airflow/dags/helpers/target_functions.py

airflow/helpers/increment.py