擅长:python、mysql、java
<p>如果您唯一的问题是空值,您可以先在<code>if</code>中检查它:</p>
<pre><code>def traverse(o, tree_types=(list, tuple)):
if isinstance(o, tree_types):
if len(o) == 0:
yield ''
for value in o:
for subvalue in traverse(value):
yield subvalue
else:
yield o
</code></pre>