From users.csv, list the distinct cities of users whose role is 'admin', into /tmp/admin_cities.txt.
Filter `/home/user/data/users.csv` to admin lines, take the 3rd column, dedupe, and save:
```
berlin
```
Pipeline idea: `grep ,admin, ... | cut -d, -f3 | sort -u > /tmp/admin_cities.txt`.
Sign in to save your code and track progress across devices.
