做自己的训练集时运行voc_annotation.py，报错'NoneType' object has no attribute 'text'

最近在学着用yoloV3，然后参照一些不错的帖子学习，这些我觉得好的帖子稍后再整理。

今天在尝试制作自己的训练集的时候，前面都顺顺利利，但是在运行voc_annotation.py时报错了，

Traceback (most recent call last):
  File "", line 1, in 
  File "E:\PyCharm 2018.3.4\helpers\pydev\_pydev_bundle\pydev_umd.py", line 197, in runfile
    pydev_imports.execfile(filename, global_vars, local_vars)  # execute the script
  File "E:\PyCharm 2018.3.4\helpers\pydev\_pydev_imps\_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "D:/yolov3/keras-yolo3-master/voc_annotation.py", line 31, in 
    convert_annotation(year, image_id, list_file)
  File "D:/yolov3/keras-yolo3-master/voc_annotation.py", line 15, in convert_annotation
    difficult = obj.find('Difficult').text
AttributeError: 'NoneType' object has no attribute 'text

查了一些帖子，最后在一篇帖子中看明白了错误的来源，就是这个，点这里看原帖，帖子中说的是标注的.XML文件里，文件部分