How does it work on the carbs that have no choke?

I've seen them before & didn't think much about it, until today & I caught part of a show where they were mounting the carb & mentioned it have no choke flaps.

Whats' the deal or do they just live where it is warm all the time???

 

I've had a few Holleys that didn't have a working choke, they seemed to work fine in cold weather where I live (seldom gets below 20 deg.F) I just had to pump it a few times and then let it warm a few min. before driving.