>#变量引用str
> s = "abc"
> s
'abc'

>#如果这样写，就会是...
> t = 123,'abc',["come","here"]
> t
(123, 'abc', ['come', 'here'])

> t = 1,"23",[123,"abc"],("python","learn")  #元素多样性，近list
> t
(1, '23', [123, 'abc'], ('python', 'learn'))

> t[0] = 8　                 #不能原地修改，近str
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment

> t.append("no") 
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
AttributeError: 'tuple' object has no attribute 'append'
  > 

> one_list = ["python","qiwsir","github","io"]
> one_list[2]
'github'
> one_list[1:]     
['qiwsir', 'github', 'io']
> for word in one_list:
...   print word
... 
python
qiwsir
github
io
> len(one_list)
4

> t
(1, '23', [123, 'abc'], ('python', 'learn'))
> t[2]
[123, 'abc']
> t[1:]
('23', [123, 'abc'], ('python', 'learn'))
> for every in t:
...   print every
... 
1
23
[123, 'abc']
('python', 'learn')
> len(t)
4

> t[2][0]   #还能这样呀，哦对了，list中也能这样
123
> t[3][1]
'learn'

> t     
(1, '23', [123, 'abc'], ('python', 'learn'))
> tls = list(t)              #tuple-->list
> tls
[1, '23', [123, 'abc'], ('python', 'learn')]

> t_tuple = tuple(tls)          #list-->tuple
> t_tuple
(1, '23', [123, 'abc'], ('python', 'learn'))