#/usr/bin/env python
sex = input("please input your sex:")
if sex == "girl":
print("alex is 1b") ==>空格表示縮進，表示一個域，官方建議四個空格
elif sex == "man":
print("alex is 2b")
else:
print("alex is 3b")運行時出現： please input your sex:girl alex is sb please input your sex:man alex is 2b
please input your sex:ddgrdgg
alex is 3b