AngleUnitSystem, PyghaCompiler, parallel.run?

Hello,
What these mean and how to use them in GhPython?
AngleUnitSystem, PyghaCompiler, parallel.run

import Rhino as rh
import GhPython as gh
import ghpythonlib as gb

rh.AngleUnitSystem.Degrees
gh.Assemblies.PyghaCompiler
gb.parallel.run