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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 libvlc_add_intf(p_instance, name):
    '''Try to start a user interface for the libvlc instance.
    @param p_instance: the instance.
    @param name: interface name, or NULL for default.
    @return: 0 on success, -1 on error.
    '''
    f = _Cfunctions.get('libvlc_add_intf', None) or \
        _Cfunction('libvlc_add_intf', ((1,), (1,),), None,
                    ctypes.c_int, Instance, ctypes.c_char_p)
    return f(p_instance, name)