text: const expect = require('expect');
  const {sample} = require('./_30s.js');
  
  test('sample is a Function', () => {
    expect(sample).toBeInstanceOf(Function);
  });
  const arr = [3, 7, 9, 11];
  test('Returns a random element from the array', () => {
    expect(arr.includes(sample(arr))).toBeTruthy();
  });
  test('Works for single-element arrays', () => {
    expect(sample([1])).toBe(1);
  });
  test('Returns undefined for empty array', () => {
    expect(sample([])).toBe(undefined);
  });
  