With python I can use
print u"\U0001F602"
to print the emoji 
but I can't print the flag 
emoji with
print u"\U0001F1F2\U0001F1FE"
because the flag is default by text style in terminal, how to print a flag emoji icon in terminal?
I tried adding the emoji variation selector but also not working for flag.
Yes as @Alastair said, it works on Terminal.app but not iTerm2.app, but set same font with both the apps, result still the same.