dynamic loop at group by

LOOP AT <lt_values> ASSIGNING <ls_value>
        GROUP BY (
            level1 = get_part( i_ls_value = <ls_value> iv_level = mv_level1 )
            level2 = get_part( i_ls_value = <ls_value> iv_level = mv_level2 )
            level3 = get_part( i_ls_value = <ls_value> iv_level = mv_level3  )
            level4 = get_part( i_ls_value = <ls_value> iv_level = mv_level4 )
            level5 = get_part( i_ls_value = <ls_value> iv_level = mv_level5 )
            level6 = get_part( i_ls_value = <ls_value> iv_level =  mv_level6 ) )
            ASCENDING
         ASSIGNING FIELD-SYMBOL(<lft_value_group>).
      CLEAR  <lt_values_group>.
      LOOP AT GROUP <lft_value_group> ASSIGNING FIELD-SYMBOL(<lfs_value_group>).
        <lt_values_group> = VALUE #( BASE  <lt_values_group> ( <lfs_value_group> ) ).

      ENDLOOP.

*** Method definition ***            
    METHODS get_part
      IMPORTING
        i_ls_value      TYPE any
        iv_level        TYPE string
      RETURNING
        VALUE(r_result) TYPE char10.  
*** Method Implementation ***
   METHOD get_part.

    IF iv_level IS NOT INITIAL.
      ASSIGN COMPONENT iv_level OF STRUCTURE i_ls_value TO FIELD-SYMBOL(<part>).

      r_result = <part>.
    ENDIF.
  ENDMETHOD.