Custom facts module question - running a copy of an ansible module from the "library" dir

Hello everyone,

I’m trying to understand how to write custom modules. For that, I’ve copied an existing ios_facts.py to a playbook library directory and renamed it to slb_facts2.
I thought that just copying the module would keep it working, however it doesn’t execute from the playbook because of the following errors.

Is something special required to run an unmodified ansble module from the /library/ dir?

Obviously main ios_facts module works fine on the same devices.

Thank you very much for suggestions.

$ cat test_facts.yml