input: Write a python function to create an Employee object, change the employee's name and salary, and return the updated salary.
  assert change_employee_details("John", 50000, "Doe", 60000) == 60000
  assert change_employee_details("Alice", 70000, "Bob", 80000) == 80000
  assert change_employee_details("Charlie", 90000, "Eve", 100000) == 100000
output: class Employee:
      def __init__(self, name, salary):
          self.name = name
          self.salary = salary
  
  def change_employee_details(initial_name, initial_salary, new_name, new_salary):
      employee = Employee(initial_name, initial_salary)
      employee.name = new_name
      employee.salary = new_salary
      return employee.salary