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Issue description

Section 9.4: Guided Exercise: Managing Users and Authentication

In step 5 and other places the content shows using "" to concatenate strings, for example: "{{ lookup('file', 'files/' item['username'] + '.key.pub') }}"

However, the jinja2 string concatenation operator is tilde, "~", which guarantees values are converted to strings before concatenation.

Course content should show consistently using tilde to avoid errors which may arise from type conflicts as documented in the jinja2 project:

https://jinja.palletsprojects.com/en/stable/templates/#math

Steps to reproduce:

Workaround:

Expected result: