Python、XML和遍历标记都不会产生任何值

我目前有一个Python程序，它打开一个XML文件，遍历标记并将内容打印到文本文件中

import xml.etree.ElementTree as etree
import xml.etree.ElementTree as ET
import tkFileDialog

#asks for the location of the file to open
file = tkFileDialog.askopenfilename()
#parse in the file
tree = ET.parse(file)
root = tree.getroot()
#asks for the location/name of court file to save as
file = tkFileDialog.asksaveasfilename()
f = open(file, 'w')
f.write("\t\t\tReport: \n\n")

#this prints out all tags and text in the right order 
iter_ = tree.getiterator()
for elem in iter_:
    #print (elem.tag, elem.text)
    f.write("\t")
    f.write(elem.tag)
    f.write(": \t\t")
    f.write(str(elem.text))
    f.write("\n")

f.close()

问题是XML文件中的一些标记没有任何用户输入，因此当程序迭代时，它不会在空间中放置任何标记，而不是将其留空

文本文件输出：

Crime Report: 

crime_report:       None
case_number:        090
victim_details:     None
victim_first_name:  j
victim_surname:     j
officer_details:    None
officer_name:       j
officer_ID_number:  j
witness_details:    None    
witness_first_name: j
witness_address:    j

当前XML文件：

<crime_report>
    <case_number caseno="unique identifier associated to the case">090
        <victim_details>
            <victim_first_name>j</victim_first_name>
            <victim_surname>j</victim_surname>
        </victim_details>
        <officer_details>
            <officer_name>j</officer_name>
            <officer_ID_number>j</officer_ID_number>
        </officer_details>
        <witness_details>
            <witness_first_name>j</witness_first_name>
            <witness_address>j</witness_address>
        </witness_details>
    </case_number>
</crime_report> 

---

我不知道如何迭代，使它们只显示为空，而不显示为无？

您能在输出代码中添加一个条件吗？如果elem.text不是无：……谢谢，我不知道为什么我不想这么做！我想我认为这会更复杂。