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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 inet_pton(address_family, ip_string):
 """ A platform independent version of inet_pton """

    global __inet_pton
    if __inet_pton is None:
        if hasattr(socket, 'inet_pton'):
            __inet_pton = socket.inet_pton
        else:
            from ospd import win_socket
            __inet_pton = win_socket.inet_pton

    return __inet_pton(address_family, ip_string)