Task
Build `star_format(situation, task, action, result)` returning a 4-part bulleted answer ready to recite:
- Format: `"S: <situation>\nT: <task>\nA: <action>\nR: <result>"` (newline-separated, in S/T/A/R order).
- Strip leading/trailing whitespace from each field.
- Reject any field that's empty after stripping β return `"INCOMPLETE"` (interviewers can smell a missing R).
- All four present β return the formatted answer.
The shape forces you to lead with the situation and CLOSE with a measurable result β the #1 fix for rambling behavioral answers.