Retrieve the instances of this `Part` as a `PartSet`.

        For instance, if you have a model part, you can get the list of instances that are created based on this
        moodel. If there are no instances (only possible if the multiplicity is :attr:`enums.Multiplicity.ZERO_MANY`)
        than a :exc:`NotFoundError` is returned

        .. versionadded:: 1.8

        :return: the instances of this part model :class:`PartSet` with category `INSTANCE`
        :raises NotFoundError: if no instances found

        Example
        -------
        >>> wheel_model = project.model('Wheel')
        >>> wheel_instance_set = wheel_model.instances()

        An example with retrieving the front wheels only using the 'name__contains' search argument.

        >>> wheel_model = project.model('Wheel')
        >>> front_wheel_instances = wheel_model.instances(name__contains='Front')

def instances(self, **kwargs):
        """
        Retrieve the instances of this `Part` as a `PartSet`.

        For instance, if you have a model part, you can get the list of instances that are created based on this
        moodel. If there are no instances (only possible if the multiplicity is :attr:`enums.Multiplicity.ZERO_MANY`)
        than a :exc:`NotFoundError` is returned

        .. versionadded:: 1.8

        :return: the instances of this part model :class:`PartSet` with category `INSTANCE`
        :raises NotFoundError: if no instances found

        Example
        -------
        >>> wheel_model = project.model('Wheel')
        >>> wheel_instance_set = wheel_model.instances()

        An example with retrieving the front wheels only using the 'name__contains' search argument.

        >>> wheel_model = project.model('Wheel')
        >>> front_wheel_instances = wheel_model.instances(name__contains='Front')

        """
        if self.category == Category.MODEL:
            return self._client.parts(model=self, category=Category.INSTANCE, **kwargs)
        else:
            raise NotFoundError("Part {} is not a model".format(self.name))