> map(lambda x : x*x, [2, 4, 8, 9])
[4, 16, 64, 81]

# 无参
> lambda : 'hello word!'
<function <lambda> at 0x10d32f578>
> hw = lambda : 'hello word!'
> hw()
'hello word!'
> hw
<function <lambda> at 0x10d32f5f0>

# 有参
> sum = lambda a, b : a + b
> sum(2, 8)
10
# 有参 有默认值
> sum = lambda a, b=8 : a + b
> sum(2)
10
> sum(2, 4)
6
# 不定长参
> sum = lambda *z : z
> sum(18, 'ac', {'a': 1})
#嵌套if else（还有其他很多使用方法）
> sum = lambda a, b : a if a>b else b
> sum(4, 5)
5