text: const employee = require('./employeeModule');
  
  // Add some base employees
  employee.addEmployee('John', 'Smith');
  employee.addEmployee('Jane', 'Smith');
  
  console.log(employee.lookupByLastName('Smith'));
  
  employee.addEmployee('William', 'Smith');
  
  console.log(employee.lookupByLastName('Smith'));
  
  let employeeId2 = employee.lookupById(2);
  
  console.log(employeeId2);
  
  employeeId2.firstName = typeof employeeId2 === 'undefined' ? undefined : 'Mary';
  
  console.log(employee.lookupByLastName('Smith'));