def METHOD_NAME(db_session, user_vimes, org_ankhmorpork, user_vetinari):
    vimes_admin = models.AccountMembership(
        member=user_vimes,
        account=org_ankhmorpork,
        granted_by=user_vetinari,
        is_owner=False,
    )
    db_session.add(vimes_admin)
    assert 'admin' in org_ankhmorpork.roles_for(user_vimes)
    return vimes_admin