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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_vlm_get_media_instance_position(p_instance, psz_name, i_instance):
    '''Get vlm_media instance position by name or instance id.
    @param p_instance: a libvlc instance.
    @param psz_name: name of vlm media instance.
    @param i_instance: instance id.
    @return: position as float or -1. on error.
    '''
    f = _Cfunctions.get('libvlc_vlm_get_media_instance_position', None) or \
        _Cfunction('libvlc_vlm_get_media_instance_position', ((1,), (1,), (1,),), None,
                    ctypes.c_float, Instance, ctypes.c_char_p, ctypes.c_int)
    return f(p_instance, psz_name, i_instance)