input: Write a python function to create an Employee class with instance variables name and age, and methods to set and display those variables.
  assert hasattr(Employee, 'name')
  assert hasattr(Employee, 'age')
  assert callable(getattr(Employee, 'set_name', None))
  assert callable(getattr(Employee, 'set_age', None))
  assert callable(getattr(Employee, 'display_info', None))
output: class Employee:
      def __init__(self, name=None, age=None):
          self.name = name
          self.age = age
  
      def set_name(self, name):
          self.name = name
  
      def set_age(self, age):
          self.age = age
  
      def display_info(self):
          print(f'Name: {self.name}, Age: {self.age}')