How to use the fmpy.ssp.ssd.System function in FMPy

if validate:
        validate_tree(root, 'SystemStructureDescription.xsd')

    ssd = SystemStructureDescription()

    ssd.version = root.get('version')
    ssd.name = root.get('name')

    # Units
    for u in root.findall('ssd:Units/ssc:Unit', namespaces=ns):
        attr = dict(u.attrib)
        bu = u.find('ssc:BaseUnit', namespaces=ns)
        attr.update(bu.attrib)
        ssd.units.append(Unit(**attr))
    ssd.system = System()

    system = root.find('ssd:System', namespaces=ns)

    ssd.system = handle_system(system, filename=filename)

    # add parent elements
    add_tree_info(ssd.system)
    ssd.system.parent = None

    return ssd

def handle_system(system, filename):
    """
    Parameters:
        system      ...
        filename    filename of the SSP file

    Returns:
        A System object
    """

    system_obj = System()

    system_obj.name = system.get('name')
    system_obj.description = system.get('description')
    _handle_element(system_obj, system, filename)

    # for b in system.findall('ssd:ParameterBindings/ssd:ParameterBinding', namespaces=ns):
    #     system_obj.parameterBindings.append(
    #         ParameterBinding(prefix=b.get('prefix'), source=b.get('source'), type=b.get('type')))

    system_obj.connectors = get_connectors(system)

    # Components
    for c in system.findall('ssd:Elements/ssd:Component', namespaces=ns):
        component = Component(name=c.get('name'), source=c.get('source'), type=c.get('type'))
        _handle_element(component, c, filename)
        component.connectors = get_connectors(c)

def add_path(element, path=''):

    if isinstance(element, System):
        for child in element.elements:
            add_path(child, path + child.name + '.')

    for connector in element.connectors:
        connector.path = path + connector.name

components = find_components(ssd.system)
    connectors = find_connectors(ssd.system)
    connections = get_connections(ssd.system)

    # resolve connections
    connections_reversed = {}

    for a, b in connections:
        connections_reversed[b] = a

    new_connections = []

    # trace connections back to the actual start connector
    for a, b in connections:

        while isinstance(a.parent, System) and a.parent.parent is not None:
            a = connections_reversed[a]

        new_connections.append((a, b))

    connections = new_connections

    # extract the SSP
    ssp_unzipdir = extract(ssp_filename)

    # initialize the connectors
    for connector in connectors:
        connector.value = 0.0

    # instantiate the FMUs
    for component in components:
        instantiate_fmu(component, ssp_unzipdir, start_time, parameter_set)

def add_tree_info(element):

    if isinstance(element, System):
        for child in element.elements:
            child.parent = element
            add_tree_info(child)

    for connector in element.connectors:
        connector.parent = element