the if statement works only if condition is true, so if b was a true it will run and return a True and else otherwise,

and if you're talking about the way he write the code this the shorthand if statement in return statement

In a=b cases, the range is basically range object with one value. and sum function looks for values inside the range object (which in this case is just one value), and sums them up.

Please correct me if i'm wrong.

This code returns string either way I guess :D