class Kullanici:
    def __init__(self,kullanici_adi):
        self.kullanici_adi=kullanici_adi
        self.takipciler=[]
        self.takip_etme=[]
        self.gonderiler=[]
        
    def follow(self,user):
        if user not in self.takip_etme:
            self.takip_etme.append(user)
            user.add_follower(self)
            
    def add_follower(self,user):
        if yuser not in self.takipciler:
            self.takipciler.append(user)
    
    def create_post(self,content):
        post=Post(content,self)
        self.gonderiler.append(ppost)
        return post
        
    def display_timeline(self):
        timeline = sorted(
            [post for user in self.takip_etme for post in user.gonderiler] + self.gonderiler,
            key=lambda post: post.timestamp,
            reverse=True
        )
        for post in timeline:
            print(f"{post.author.kullanici_adi}: {post.content} - {post.timestamp}")
            
class Post:
    import datetime
    
    def __init__(self,content, author):
        self.content=content
        self.author=author
        self.timestamp=self.datetime.datetime.now()
        
user1=Kullanici("Ali")
user2=Kullanici("Bekir")
user3=Kullanici("Omer")

user1.follow(user2)
user2.follow(user1)
user3.follow(user3)

post1.user2.create_post("Merhaba Ali!")
post2.user3.create_post("Merhaba Omer!")
post3.user1.create_post("Merhaba Bekir!")