How to submit/save BootSourceSelections by using python-libmaas

Hi,
I can select and update image from MAAS GUI.

I could select image but couldn't update selection with python-libmaas library.

For example, when you call image create function , the image is selected.
`session.BootSourceSelections.create(boot_source_id=1, os='ubuntu', release='xenial',arches='amd64')`

There is no include update selection function in python-libmaas

I could not update selection with the following functions

How can I do the image save or submit operation?