Using ProgressBar class

Using ProgressBar class

I'm not following how to use the UI type ProgressBar in pyMel.
The old way, or the derivative of this was to do this:
cmds.progressBar('barName', edit=1, progress=50)
However I can't seem to figure out how to use the pymel version of this.
This is what I've tried:
ProgressBar('barName').setProgress(50)
This doesn't work obviously, however I'd much rather use the pymel
version, it's cleaner and easier to read.