1. 一個(gè)元組的多元素賦值可以寫(xiě)或不寫(xiě)括號(hào)，最好還是寫(xiě)括號(hào)，比較好記。但是單個(gè)元素賦值一定要加括號(hào)和逗號(hào)，不然會(huì)識(shí)別為字符串str。
2. 比較神奇的是，這東西tuple竟然可以是空的。但它又不能改，暫時(shí)沒(méi)想到咋用。

# tuple with multiple values
>>> t = 'a', 'b', 'c', 'd', 'e'
>>>type(t)
<class 'tuple'>

>>> t1 = 'a', 'b', 'c', 'd', 'e'
>>>type(t1)
<class 'tuple'>

# tuple with a single value

>>>t2 = ('a',)
>>>type(t2)
<class 'tuple'>

>>>t3 = ('a')
>>>type(t3)
<class 'str'>  ### this is a string 

# an empty tuple with no value

>>>t4 = ()
>>>type(t4)
<class 'tuple'>

3. 記錄一下“一行賦值加累加”的代碼，get+tuple+初始值。馬克一下py4e的作業(yè)。

# open a file
# name = input("Please Enter filename:")
name = 'mbox-short.txt'
if len(name) < 1 : name = "mbox-short.txt"
try:
    handle = open(name)
except:
    print('Please input the correct filename')

# print the hours and email counts
hour_count = dict()
for line in handle:
    if line.startswith('From '):
        words_of_line = line.strip().split()
        hours = words_of_line[5][0:2]
        hour_count[hours] = 1 + hour_count.get(hours,0)

hour_count = sorted([(k,v) for k,v in hour_count.items()])

for k,v in hour_count:
    print(k,v)

#        print(hours) the hours were correct
#        sum the counts