Python has optimized string appending in the form of: s = s + "foo" and s += "foo" Since 2005 with the release of Python 2.4: https://docs.python.org/3/wha

Python has optimized string appending in the form of: s = s + "foo" and s += "foo" Since 2005 with the release of Python 2.4: https://docs.python.org/3/whatsnew/2.4.html#optimizations https://docs.python.org/3/whatsnew/2.4.html#optimizations