from sqlalchemy import Column, Integer, String from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class User(Base): __tablename__ = 'users' id = Column(Integer, primary_key=True) username = Column(String(50), nullable=False) email = Column(String(120), unique=True, nullable=False) password_hash = Column(String(128), nullable=False) def __repr__(self): return 'In this example, the User class inherits from the declarative_base class provided by SQLAlchemy, which sets up the mapping between the Python class and the database table. The __tablename__ attribute specifies the name of the table in the database, and each of the class attributes specifies a column in the table. The id, username, email, and password_hash columns are defined as SQLAlchemy Column objects, which define the data type and constraints for each column. The __repr__ method is used to provide a string representation of the class for debugging purposes. Overall, database_setup provides a flexible, high-level way to define database schema in Python code, which can help make application development faster and more efficient.' % self.username