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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_rewrite_setup(toolset, setup_script, setup_options, version, rewrite_setup='off'):
 """ Helper rule to generate a faster alternative to MSVC setup scripts. We used to call MSVC setup scripts directly in every action, however in newer MSVC versions (10.0+) they make long-lasting registry queries which have a significant impact on build time. """

    result = '"{}" {}'.format(setup_script, setup_options)

    # At the moment we only know how to rewrite scripts with cmd shell.
    if os.name == 'nt' and rewrite_setup != 'off':
        basename = os.path.basename(setup_script)
        filename, _ = os.path.splitext(basename)
        setup_script_id = 'b2_{}_{}_{}'.format(toolset, version, filename)
        if setup_options:
            setup_script_id = '{}_{}'.format(setup_script_id, setup_options)

        tempdir = os.environ.get('TEMP')
        replacement = os.path.join(tempdir, setup_script_id + '.cmd')
        if rewrite_setup == 'always' or not os.path.exists(replacement):
            import subprocess
            # call the setup script and print the environment after doing so
            p = subprocess.Popen([
                    setup_script, setup_options, '>', 'nul', '&&', 'set',
                ], stdout=subprocess.PIPE, shell=True
            )
            stdout, _ = p.communicate()

            diff_vars = []
            for var in stdout.splitlines():
                # returns a tuple of ('var-name', '=', 'value').
                # partition is being used here (over something like .split())
                # for two reasons:
                #     1) an environment variable may have a value that contains an '=';
                #        .partition() will still return the correct key and value pair.
                #     2) if the line doesn't contain an '=' at all, then the returned
                #        tuple will contain only empty strings rather than raising
                #        an exception.
                key, _, value = var.partition('=')
                # os.environ handles casing differences here. Usually the
                # call to "set" above will produce pascal-cased environment
                # variable names, so a normal python dict can't be used here.
                # check for the existence of key in case the partitioning() above
                # returned an empty key value pair.
                if key and os.environ.get(key) != value:
                    diff_vars.append('SET {}={}'.format(key, value))

            if diff_vars:
                with open(replacement, 'wb') as f:
                    f.write(os.linesep.join(diff_vars))

                result = '"{}"'.format(replacement)
        else:
            result = '"{}"'.format(replacement)

    return result