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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 mss(**kwargs):
 # type: (Any) -> MSSMixin """ Factory returning a proper MSS class instance. It detects the plateform we are running on and choose the most adapted mss_class to take screenshots. It then proxies its arguments to the class for instantiation. """


    os_ = platform.system().lower()

    if os_ == "darwin":
        from . import darwin

        return darwin.MSS(**kwargs)

    if os_ == "linux":
        from . import linux

        return linux.MSS(**kwargs)

    if os_ == "windows":
        from . import windows

        return windows.MSS(**kwargs)

    raise ScreenShotError("System {!r} not (yet?) implemented.".format(os_))