text: from uuid import uuid4
  from sqlalchemy import Column
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.dialects.postgresql import UUID, JSON
  
  from sqlalchemy_utc import UtcDateTime, utcnow
  
  from .db import engine
  
  Base = declarative_base()
  
  class Comment(Base):
      id = Column(UUID(as_uuid=True), default=uuid4, primary_key=True)
      author_id = Column(UUID(as_uuid=True), nullable=False)
      target_id = Column(UUID(as_uuid=True), nullable=False, )
      created_at = Column(UtcDateTime(), nullable=False, default=utcnow())
      comment = Column(JSON(), nullable=False)
  
      __tablename__ = 'comments'
  
  
  Base.metadata.create_all(engine)
  