Removing an irule from a group of Virtual servers in bulk

Not sure if anyone answered your question but I am running v10 as well and to get it to work I had to replace the double use of single quotes with underscore. So the method should look like this:

tmsh::get_field_value

You must also do the same for set vips_in_play at line 10. Hopefully that helps out if you haven't fixed it yourself already.