input: Write a python function to create a Department object, add employees to it, set a budget, and verify the changes.
  ```python
  def test_department():
      dept = Department("IT")
      dept.set_name("HR")
      assert dept.name == "HR"
      
      dept.add_employee("Alice")
      dept.add_employee("Bob")
      assert dept.employees == ["Alice", "Bob"]
      
      dept.set_budget(50000)
      assert dept.budget == 50000
  
  test_department()
output: class Department:
      def __init__(self, name):
          self.name = name
          self.employees = []
          self.budget = 0
  
      def set_name(self, name):
          self.name = name
  
      def add_employee(self, employee):
          self.employees.append(employee)
  
      def set_budget(self, budget):
          self.budget = budget
  
  def test_department():
      dept = Department("IT")
      dept.set_name("HR")
      assert dept.name == "HR"
      
      dept.add_employee("Alice")
      dept.add_employee("Bob")
      assert dept.employees == ["Alice", "Bob"]
      
      dept.set_budget(50000)
      assert dept.budget == 50000
  
  test_department()