变量名尽量不要和关键字相同，否则容易出歧义
>>> xm
['zhang3', 'li4', 'wang5', 'zhao6']
>>> ' '.join(str(e) for e in xm)
Traceback (most recent call last):
File "<pyshell#183>", line 1, in <module>
' '.join(str(e) for e in xm)
File "<pyshell#183>", line 1, in <genexpr>
' '.join(str(e) for e in xm)
TypeError: 'str' object is not callable
>>> str
'a'
>>> del str # 删除del变量
>>> str
<class 'str'>
>>> ' '.join(str(e) for e in xm)
'zhang3 li4 wang5 zhao6'
标签：join,xm,关键字,str,变量名,歧义 From： https://www.cnblogs.com/sangern/p/17361760.html