def METHOD_NAME(ursulas):
    ursula = list(ursulas)[0]
    # Before we start learning, Ursula has no teacher.
    assert ursula._current_teacher_node is None
    # Once we start, Ursula picks a teacher node.
    ursula.learn_from_teacher_node()
    first_teacher = ursula._current_teacher_node
    # When she learns the second time, it's from a different teacher.
    ursula.learn_from_teacher_node()
    second_teacher = ursula._current_teacher_node
    assert first_teacher != second_teacher