text: """SQLAlchemy models and database architecture"""
  
  from flask_sqlalchemy import SQLAlchemy
  
  DB = SQLAlchemy()
  
  
  # Creates a 'user' Table
  class User(DB.Model):
      # id primary key column for 'user'
      id = DB.Column(DB.BigInteger, primary_key=True)
      # username column for 'user'
      username = DB.Column(DB.String, nullable=False)
      # stores most recent tweet_id 
      newest_tweet_id = DB.Column(DB.BigInteger)
  
      def __repr__(self):
          return f"<User: {self.username}>"
  
  
  # Creates a 'tweet' Table
  class Tweet(DB.Model):
      # id primary key column for 'tweet'
      id = DB.Column(DB.BigInteger, primary_key=True)
      # text column for 'tweet'
      text = DB.Column(DB.Unicode(300))
      # stores numbers that represents tweets
      vect = DB.Column(DB.PickleType, nullable=False)
      # user_id foreign key column for 'tweet'
      user_id = DB.Column(DB.BigInteger, DB.ForeignKey(
          'user.id'), nullable=False)
  
      ### TODO: STRETCH GOAL ###
      user = DB.relationship('User', backref=DB.backref('tweets', lazy=True))
  
      def __repr__(self):
          return f"<Tweet: {self.text}>"