How to use the pynetbox.models.dcim function in pynetbox

def test_get_units(self, mock):
        test = nb.racks.get(1)
        ret = test.units.list()
        mock.assert_called_with(
            'http://localhost:8000/api/dcim/racks/1/units/',
            headers=HEADERS,
            verify=True,
        )
        self.assertTrue(ret)
        self.assertTrue(
            isinstance(ret[0].device, pynetbox.models.dcim.Devices)
        )

""" Represents apps in NetBox.

    Calls to attributes are returned as Endpoint objects.

    :returns: :py:class:`.Endpoint` matching requested attribute.
    :raises: :py:class:`.RequestError`
        if requested endpoint doesn't exist.
    """
    def __init__(self, api, name):
        self.api = api
        self.name = name
        self._choices = None
        self._setmodel()

    models = {
        "dcim": dcim,
        "ipam": ipam,
        "circuits": circuits,
        "virtualization": virtualization,
        "extras": extras
    }

    def _setmodel(self):
        self.model = App.models[self.name] if self.name in App.models else None

    def __getstate__(self):
        return {
            'api': self.api,
            'name': self.name,
            '_choices': self._choices
        }