def METHOD_NAME(self, session):
    error = session.assign(session.staff_two.id, session.job_one.id)
    assert error
    error = session.assign(session.staff_three.id, session.job_four.id)
    assert not error
    error = session.assign(session.staff_four.id, session.job_four.id)
    assert not error
    error = session.assign(session.staff_four.id, session.job_four.id)
    assert error