Phyton set active bone in posemode

Hi everyone,

how can I set a bone in pose as active bone with phyton?
I could set the first bone with it

bpy.data.objects[“mcrig”].data.bones[“Torso”].select = True

but if I try to set another bone as active its not working.

Maybe someone of you could help me. That would be nice.

I use Blender 2.82