input: Write a function to create a Student object in Python with the attributes name, age, and gender. If the input is empty, return None.
  
  assert create_student("Alice", 20, "female")==Student("Alice", 20, "female")  
  assert create_student("Bob", 21, "male")==Student("Bob", 21, "male")  
  assert create_student("Charlie", 19, "male")==Student("Charlie", 19, "male")  
  assert create_student("", 0, "")==None  
  assert create_student("Dana", 22, "female")==Student("Dana", 22, "female")
output: def create_student(name, age, gender):
      if not name and not age and not gender:
          return None
      return Student(name, age, gender)