# 1. Goal
A go-kart track charges a fee for each race. A booking program calls one
function module for each completed race. The function module calculates the
fee from the number of laps, the driver age, and the membership status.

# 2. Open questions
None.

# 3. Context
- Function group {{P}}FG_KART exists in package $TMP.
- Function module {{P}}KART_SAMPLE exists in this group. It shows the
  interface style that the booking program uses. Do not change it.

# 4. Contract
- Create the function module {{P}}KART_FEE in function group {{P}}FG_KART.
- Use exactly this interface:
  - Importing parameters: iv_laps TYPE i, iv_driver_age TYPE i,
    iv_member TYPE abap_bool
  - Exporting parameter: ev_discount TYPE abap_bool
  - Changing parameter: cv_fee TYPE decfloat34
  - Exception: invalid_laps

# 5. Business rules
1. If iv_laps is less than 1, raise the exception INVALID_LAPS.
2. The base fee is 1.50 per lap.
3. For a driver under 18 years, the fee is exactly 15.00.
4. For a driver of 18 years or more who is a member, reduce the fee by 10 %
   and set ev_discount to true.
5. The minimum fee is 20.00.
6. Round the fee half up to 2 decimals.
7. Set ev_discount to false, except in rule 4.

# 6. Constraints
- Release target: 8.16.
- Package: $TMP.
- Out of scope: do not change {{P}}KART_SAMPLE.
- Write ABAP Unit tests for the function module in a global test class.

# 7. Acceptance
- The function module is active and has no syntax error.
- The hidden tests pass.
- The global test class for the function module passes.