def addstuff():
a1 = A(name="first a")
a2 = A(name="second a")
b1 = B(name="first b", a=a1)
b2 = B(name="second b", a=a1)
b3 = B(name="third b", a=a2)
session = Session()
session.add_all([a1, a2, b1, b2, b3])
version = models.Version()
version.created = datetime.datetime.now()
session.add(version)
session.flush()
version_id = version.version_id
session.commit()
session = Session()
for op in session.query(models.Operation):
op.version_id = version_id
session.commit()
