Comment 1 for bug 1885712

The idea was to make it easier to write tests for these functions and also not accidentally update a dict in place that for some reason doesn't end up getting replaced by the caller. Possibly these are not worth all the extra boilerplate.

I thought of writing a decorator to handle this, but then you have code that looks like it's updating in place when it isn't.

Only one of these functions is being tested so far, so it wouldn't be too much work to change.