[REFACTOR] [Hacker Rank] Interview Preparation Kit: Recursion: Fibonacci Numbers.

* Adjusted the interface to match what hackerrank expects.

Author: sir-gon

src/hackerrank/interview_preparation_kit/recursion_and_backtracking/ctci_fibonacci_numbers.js

@@ -2,7 +2,7 @@
  * @link Problem definition [[docs/hackerrank/interview_preparation_kit/recursion_and_backtracking/ctci_fibonacci_numbers.md]]
  */
 
-export function fibonacci(n) {
+function fibonacci(n) {
   if (n === 0) {
     return 0;
   }

src/hackerrank/interview_preparation_kit/recursion_and_backtracking/ctci_fibonacci_numbers.test.js

@@ -1,15 +1,15 @@
 import { describe, expect, it } from '@jest/globals';
 import { logger as console } from '../../../logger.js';
 
-import { fibonacci } from './ctci_fibonacci_numbers.js';
+import fibonacciNumbers from './ctci_fibonacci_numbers.js';
 import TEST_CASES from './ctci_fibonacci_numbers.testcases.json';
 
 describe('ctci_fibonacci_numbers', () => {
   it('fibonacci test cases', () => {
     expect.assertions(3);
 
     TEST_CASES.forEach((test) => {
-      const answer = fibonacci(test.input);
+      const answer = fibonacciNumbers.fibonacci(test.input);
 
       console.debug(`fibonacci(${test.input}) solution found: ${answer}`);