Python字符串反向切片

str[start:stop:step]
反向切片时，start > stop,step < 0.

str = [0,1,2,3,4,5,6]

print(str[::-1])       #[6, 5, 4, 3, 2, 1, 0]
print(str[-1::-1])     #[6, 5, 4, 3, 2, 1,0]
print(str[-1:0:-1])    #[6, 5, 4, 3, 2, 1]
print(str[-2:1:-1])    #[5, 4, 3, 2]
print(str[-2::-2])     #[5, 3, 1]
print(str[-2:0:-2])    #[5, 3, 1]
print(str[-2:1:-2])    #[5, 3]

(待完善)