write me a simple flask application which has:
1. user authentication
2. session management
3. login page
4. sign-in page
5. a functional database - to store data of users like e-mail address and username, password
6.  another database to store post history and a folder where the uplaoded images are stored
7. all in all build me a simple twitter/reddit clone using flask Give two different versions of responses. Please separate the responses with 6 asterisk symbols: ******.
user