text: const expect = require('expect');
  const {insertBefore} = require('./_30s.js');
  
  test('insertBefore is a Function', () => {
    expect(insertBefore).toBeInstanceOf(Function);
  });
  let e = document.createElement('div');
  e.setAttribute("id", "test");
  test('Does not throw error if the element exists', () => {
    expect(() => {
      insertBefore(e, '<span>test</span>');
    }).not.toThrow(TypeError);
  });
  