How much Python have you ever written or reviewed? With only a bit of experience, I am sure you'd have no trouble doing that if the Python code is not using 2-space indentation.
It certainly becomes a problem if you are looking at a 100+ line method/function, but with Python being as expressive as it is, a 100+ line method/function is a problem unto itself.
Otherwise, I've never had any issues with it — even with languages other than Python, I mostly rely on white space and alignment to understand the block boundaries, only resorting to reviewing the braces carefully when something is amiss.
It certainly becomes a problem if you are looking at a 100+ line method/function, but with Python being as expressive as it is, a 100+ line method/function is a problem unto itself.
Otherwise, I've never had any issues with it — even with languages other than Python, I mostly rely on white space and alignment to understand the block boundaries, only resorting to reviewing the braces carefully when something is amiss.