The maxval, poll, and currval deprecation warnings used stacklevel=1, so they named progressbar's own source instead of the line that used the old name. A fixed stacklevel=2 would only be right for currval: _apply_deprecated_aliases is reached through ProgressBar.__init__ and any subclass __init__ chain above it, so the depth varies per caller. _caller_stacklevel() walks the frames from the warning site outward until the code is no longer inside the progressbar package and returns that depth. Five tests record the warning and assert its filename and line are the caller's, for a plain bar, a DataTransferBar, a user subclass with its own __init__, and the currval property.

…tions