Python instance variable

I picked up these lines of code from a model answer to a textbook question

if self._initialSum == 0:
        initialSum = v1 + v2
        if initialSum in (2, 3, 12):
            return "LOSE"
        elif initialSum in (7, 11):
            return "WIN"
        else:
            return "CONTINUE"
    else:
        sum = v1 + v2
        if sum == 7:
            return "LOSE"
        elif sum == initialSum:
            return "WIN"
        else:
            return "CONTINUE"

I am trying to figure out of self.initialSum and initialSum are referencing the same variable. My beginner understanding is the main if block and else block each have a initialSum however the else block is referencing it before it is set. Or is it set by self._initialSum.

I hope I am making sense guys. Thanks in advance

Kimmy