博主您好，在eval.py中有一小句代码（tag='0' if tag=='O' else tag）看不太懂，博主您是否能解释一下呢。这里都把tag的值赋为0了为什么还要检测是不是为'O'呢？

[YuQuankun]

with open(label_path, "w") as fw:
line = []
for sent_result in label_predict:
for char, tag, tag_ in sent_result:
tag = '0' if tag == 'O' else tag
char = char.encode("utf-8")
line.append("{} {} {}\n".format(char, tag, tag_))
line.append("\n")
fw.writelines(line)