1.len()
>>> s = set('aaa')
>>> s
{'a'}<span style="white-space:pre"> </span>#集合不重复性质
>>> len(s)
1>>> s = set('aaa')
>>> s
{'a'}<spa1.len()
>>> s = set('aaa')
>>> s
{'a'}<span style="white-space:pre"> </span>#集合不重复性质
>>> len(s)
1>>> s = set('aaa')
>>> s
{'a'}<spa