text: from sqlalchemy import create_engine
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.orm import sessionmaker
  
  
  Base = declarative_base()
  Engine = None
  Session = None
  
  
  def setup(url):
      global Engine
      global Session
      Engine = create_engine(url)
      Base.metadata.create_all(Engine)
      Session = sessionmaker(Engine)
      return Session
  
  def create_session():
      global Session
      if not Session:
          Session = sessionmaker(Engine)
      return Session()