import os

from sqlalchemy.ext.automap import automap_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from sqlalchemy.orm.scoping import scoped_session

DB_URL = os.environ['DB_URL']
Base = automap_base()
engine = create_engine(DB_URL)
Base.prepare(engine, reflect=True)

session_factory  = sessionmaker(bind=engine, expire_on_commit=False)
Session = scoped_session(session_factory)
import os

from sqlalchemy.ext.automap import automap_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from sqlalchemy.orm.scoping import scoped_session

DB_URL = os.environ['DB_URL']

if not DB_URL:
    raise ValueError("DB_URL not present in the environment")

Base = automap_base()
engine = create_engine(DB_URL)
Base.prepare(engine, reflect=True)

session_factory  = sessionmaker(bind=engine, expire_on_commit=False)
Session = scoped_session(session_factory)
Test for DB_URL being present in environment.
Test for DB_URL being present in environment.

  import os
  
  from sqlalchemy.ext.automap import automap_base
  from sqlalchemy.orm import sessionmaker
  from sqlalchemy import create_engine
  from sqlalchemy.orm.scoping import scoped_session
  
  DB_URL = os.environ['DB_URL']
+ 
+ if not DB_URL:
+     raise ValueError("DB_URL not present in the environment")
+ 
  Base = automap_base()
  engine = create_engine(DB_URL)
  Base.prepare(engine, reflect=True)
  
  session_factory  = sessionmaker(bind=engine, expire_on_commit=False)
  Session = scoped_session(session_factory)
Test for DB_URL being present in environment.
## Code Before:
import os

from sqlalchemy.ext.automap import automap_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from sqlalchemy.orm.scoping import scoped_session

DB_URL = os.environ['DB_URL']
Base = automap_base()
engine = create_engine(DB_URL)
Base.prepare(engine, reflect=True)

session_factory  = sessionmaker(bind=engine, expire_on_commit=False)
Session = scoped_session(session_factory)
## Instruction:
Test for DB_URL being present in environment.
## Code After:
import os

from sqlalchemy.ext.automap import automap_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from sqlalchemy.orm.scoping import scoped_session

DB_URL = os.environ['DB_URL']

if not DB_URL:
    raise ValueError("DB_URL not present in the environment")

Base = automap_base()
engine = create_engine(DB_URL)
Base.prepare(engine, reflect=True)

session_factory  = sessionmaker(bind=engine, expire_on_commit=False)
Session = scoped_session(session_factory)