How to make for loop faster in python?

How hard is it to port an application from Python 2 to make it work in Python 3? Make it backward compatible. Say the program consists of 50 Python files and everything connected with each.

• And if there any libraries and any *tricks* to make it much easier,please add them.

• Answer:

  Depends on what libraries and external interfaces are in use in the Python 2 code.   If the Python 2 program is purely Python, then 2to3 is going to get you much of the way to Python 3, if not all the way.   But if you don't have a decent set of regression tests laying around for your app, you aren't going to sleep soundly until you work out a suite of tests for the Python 3 incarnation of your program. But if your program has lots of embedded C code, and passes to C routines strings that are now going to be in Unicode, and if you have dependencies on library modules that just haven't yet made their way to the Python 3 side of the ledger, then 2to3 is going to be a mere down payment on the conversion of your app from Python 2 to Python 3.