Coming from C++ I guess the question is does the underlying implementation when sent to a exe maker such as py2exe or when interpretted take into account things like memory allocation etc. While in this case storing all values is trivial what about in cases where hte list could potentially be thousands of items long. Even with the use of iterables we're talking about a memory. I assume you could say the comparison can either be done in loop or @ the end as this code does.