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?

Start with the documented session.BootSourceSelections.create call and the BootSourceSelections API referenced in the issue. Determine whether the library exposes a save or submit operation for an existing selection, then document the supported workflow or identify the missing operation. The issue provides no file or test location, so repository-wide API and documentation search is required.

索引モデルが issue の本文から書いたものです。