如何获取相同级别的下一个直接xml节点

Question

我正在使用ElementTree在python中解析此XML文件。

<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="
    http://www.springframework.org/schema/webflow
    http://www.springframework.org/schema/webflow/spring-webflow-2.0.xsd">

<secured attributes="ROLE_USER" />

<input name="hotelId" required="true" />

<on-start>
    <evaluate expression="bookingService.createBooking(hotelId, currentUser.name)" result="flowScope.booking" />
</on-start>

<view-state id="enterBookingDetails" model="booking">
    <transition on="proceed" to="reviewBooking" />
    <transition on="cancel" to="bookingCancelled" bind="false" />
</view-state>

<view-state id="reviewBooking">
    <transition on="confirm" to="bookingConfirmed">
        <evaluate expression="bookingService.persistBooking(booking)" />
    </transition>
    <transition on="revise" to="enterBookingDetails" />
    <transition on="cancel" to="bookingCancelled" />
</view-state>

<end-state id="bookingConfirmed" />

<end-state id="bookingCancelled" />

</flow>

我需要紧靠<on-start>节点的节点，但是该节点必须是Spring Webflow状态节点，即<view-state>，<action-state>或<decision-state>等。如何使用ElementTree做到这一点？