How to set a Python set as a secret?

Which format should I use if I want pass a “Python set” as a workflow secret?

The set(UID_UNAME) is composed of uid(numeric) and name:
{‘222 tom’,
‘333 jack’}

This is how it is quoted in script:
UID_UNAME = os.environ[“UID_UNAME”]

What should I paste in the secret box?
The word ‘set’ is quite misleading for finding an answers.