lambda:
def is_odd(n):
return n % 2 == 1
L = list(filter(is_odd, range(1, 20)))
print(L)
print(list(filter(lambda n: n % 2 == 1, range(1, 20))))
递归：
def fact(n):
if n == 1:
return n
else:
return fact(n-1) + n
print(fact(100))
#fact(3) = fact(2) + 3 = fact(1) + 2 + 3
