This feels wrong.  `db2.execute()` should handle the argument insertion. Is `fakedata.featured_versions` a tuple of strings? In that case, you should be able to use 
```
db2.execute(
    "UPDATE product_versions SET featured_version = TRUE "
    "WHERE version_string IN (%s, %s, %s, %s)",
    fakedata.featured_versions
)
```