input: Write a function that takes an Employee class instance as input and checks if the job title is "Manager". If the job title is "Manager", return True; otherwise, return False. The function should also handle the case where the input is not an instance of the Employee class by raising a ValueError.
  assert check_manager(Employee("John Doe", "Manager", 123)) == True
  assert check_manager(Employee("Jane Smith", "Developer", 456)) == False
  assert check_manager("Not an employee") == ValueError
output: def check_manager(employee):
      if not isinstance(employee, Employee):
          raise ValueError("Input is not an instance of the Employee class")
      return employee.job_title == "Manager"