str.strip([chars])
Return a copy of the string with the leading and trailing characters removed.
The chars argument is a string specifying the set of characters to be removed.
If omitted or None, the chars argument defaults to removing whitespace.
The chars argument is not a prefix or suffix; rather, all combinations of its
values are stripped:>>> ' spacious '.strip()
'spacious'
>>> 'www.example.com'.strip('cmowz.')
'example'
就是，如果省略参数，默认过滤空格。
#过滤list中的偶数
def get_odd(s):
return s % 2 == 1; #C语言绝对不能这么写
print "get odd:", filter(get_odd, [1, 2, 3, 4, 5, 6])
#过滤list中的空格
def not_empty(s):
return s and s.strip() #s过滤了'None'元素，s.strip()默认过滤空格
print "not_empty:", filter(not_empty, ['A', ' ', 'B', None, 'C', ' '])
