GhPython code for finding the KangarooSolver.dll that Rhino 6/7/8 ship with and importing it properly in most settings.

Kangaroo2AssemblySelector.py

import Rhino
import clr
import os

if "KangarooSolver" in str(clr.References):
    import KangarooSolver as ks
else:
    try:
        rhino_version = Rhino.RhinoApp.ExeVersion
        if os.name == "nt":
            if rhino_version == 6:
                k2ap = ("C:/Program Files/Rhino 6/Plug-ins/Grasshopper/"
                        "Components/KangarooSolver.dll")
                clr.AddReferenceToFileAndPath(os.path.normpath(k2ap))
            elif rhino_version == 7:
                k2ap = ("C:/Program Files/Rhino 7/Plug-ins/Grasshopper/"
                        "Components/KangarooSolver.dll")
                if not os.path.exists(k2ap):
                    k2ap = ("C:/Program Files/Rhino 7 WIP/Plug-ins/Grasshopper/"
                            "Components/KangarooSolver.dll")
                clr.AddReferenceToFileAndPath(os.path.normpath(k2ap))
            elif rhino_version == 8:
                k2ap = ("C:/Program Files/Rhino 8/Plug-ins/Grasshopper/"
                        "Components/KangarooSolver.dll")
                if not os.path.exists(k2ap):
                    k2ap = ("C:/Program Files/Rhino 8 WIP/Plug-ins/Grasshopper/"
                            "Components/KangarooSolver.dll")
                clr.AddReferenceToFileAndPath(os.path.normpath(k2ap))
        elif os.name == "posix":
            if rhino_version == 7:
                k2ap = ("/Applications/Rhinoceros.app/Contents/Frameworks/"
                        "RhCore.framework/Versions/A/Resources/ManagedPlugIns/"
                        "GrasshopperPlugin.rhp/Components/KangarooSolver.dll")
                clr.AddReferenceToFileAndPath(os.path.normpath(k2ap))
            elif rhino_version == 8:
                k2ap = ("/Applications/RhinoWIP.app/Contents/Frameworks/"
                        "RhCore.framework/Versions/A/Resources/ManagedPlugIns/"
                        "GrasshopperPlugin.rhp/Components/KangarooSolver.dll")
                clr.AddReferenceToFileAndPath(os.path.normpath(k2ap))
        import KangarooSolver as ks
    except (IOError, ImportError):
        try:
            clr.AddReferenceToFile("KangarooSolver.dll")
            import KangarooSolver as ks
        except (IOError, ImportError):
            raise RuntimeError("KangarooSolver.dll was not found! please add the "
                               "folder to your module search paths manually!")