FUNCTION {{p}}key_price
  IMPORTING
    iv_key_type TYPE string
    iv_quantity TYPE i
  EXPORTING
    ev_price TYPE decfloat34
    ev_valid TYPE abap_bool
  EXCEPTIONS
    invalid_quantity.

  DATA lv_unit_price TYPE decfloat34.
  ev_price = 0.
  ev_valid = abap_false.
  IF iv_quantity < 1.
    RAISE invalid_quantity.
  ENDIF.
  CASE iv_key_type.
    WHEN 'ST'.
      lv_unit_price = '3.50'.
    WHEN 'SE'.
      lv_unit_price = '12.00'.
    WHEN 'TR'.
      lv_unit_price = '45.00'.
    WHEN OTHERS.
      RETURN.
  ENDCASE.
  ev_price = lv_unit_price * iv_quantity.
  IF iv_quantity >= 10.
    ev_price = ev_price * '0.9'.
  ENDIF.
  ev_price = round( val = ev_price dec = 2 mode = cl_abap_math=>round_half_up ).
  ev_valid = abap_true.

ENDFUNCTION.