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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def maybe_2to3(filename, modname=None):
 """Returns a python3 version of filename."""

    need_2to3 = False
    filename = os.path.abspath(filename)
    if any(filename.startswith(d) for d in DIRS):
        need_2to3 = True
    elif modname is not None and any(modname.startswith(p) for p in PACKAGES):
        need_2to3 = True
    if not need_2to3:
        return filename
    outfilename = '/_auto2to3_'.join(os.path.split(filename))
    if (not os.path.exists(outfilename) or
        os.stat(filename).st_mtime > os.stat(outfilename).st_mtime):
        try:
            with open(filename) as file:
                contents = file.read()
            contents = rt.refactor_docstring(contents, filename)
            tree = rt.refactor_string(contents, filename)
        except Exception as err:
            raise ImportError("2to3 couldn't convert %r" % filename)
        outfile = open(outfilename, 'wb')
        outfile.write(str(tree).encode('utf8'))
        outfile.close()
    return outfilename