You could make read_portfolio a generator ( https://wiki.python.org/moin/Generators https://wiki.python.org/moin/Generators ). But that might confuse inexperien

You could make read_portfolio a generator ( https://wiki.python.org/moin/Generators https://wiki.python.org/moin/Generators ). But that might confuse inexperienced Python programmers. Personally the way you've done it is the most Pythonic IMO. List comprehensions are great but would be less readable in this case.