UNDO "Make this the only selectable layer"

[Nabaz_Gharib]

this question was asked 4 years ago, but still no solution. 
Solved: UNDO "Make this the only selectable layer" - Esri Community

apparently, it should be simple and straightforward, but practically it is a pain.

I have 4 CAD layers in a map, and I made one of them as only selectable, the problem is the CAD files are groups within groups. now when I want to make all layer selectable I have to go to all groups expand them and make all of the selectable. 

this procedure is fine for on time, but for several time it is simply a pain. I looked at arcpy to find away iterate over layer to make all of them selectable but could not find  a solution.

The requested feature us add a command to make all layers (supported layers) selectable. 

[AlfredBaldenweck]

Related: Turn off editing, selection for group layers - Esri Community

[-_-]

It is possible to do this using CIM access, but it takes a bit of time, so I would appreciate it if there were a better way to do it.

import arcpy

aprx=arcpy.mp.ArcGISProject("CURRENT")

view=aprx.activeView

mapname=view.map.name
maps=aprx.listMaps(mapname)[0]
lyrs=maps.listLayers()

for l in lyrs:
    l_cim=l.getDefinition('V3')
    try:
        if l_cim.selectable:
            continue
        else:
            l_cim.selectable=True

            l.setDefinition(l_cim)
    except:
        continue