Alternative to the clunky 2to3 command line script. Streamlined function that will take a Python 2 code string (as unicode), feed it through lib2to3 using all its converters, then return a Python 3 code string.

convert2to3.py

# coding: utf-8

import lib2to3
import lib2to3.fixes
import lib2to3.refactor

__all__ = ["code_to_py3"]

all_fixes = ["lib2to3.fixes.fix_{}".format(l)
             for l in lib2to3.refactor.get_all_fix_names("lib2to3.fixes")]
tool = lib2to3.refactor.RefactoringTool(all_fixes,
                                        options={'print_function': False})

def code_to_py3(code_block):
    # + "\n" to make it parse, then [:-1] to chop off tacked-on \n
    return tool.refactor_string(code_block + u"\n",
                                "<script>")[:-1]