How to set Units and render engine via script?

So… How to set Units and render engine via script?
This is what I managed to write… not working, of course.

bpy.context.scene.unit_settings.system

Blender 2.62

I don’t understand, how to use this documentation: http://www.blender.org/documentation/blender_python_api_2_62_3/bpy.types.UnitSettings.html?highlight=unit_settings

Thank you!

hi!!

for change render engine

bpy.context.scene.render.engine="BLENDER_RENDER"
bpy.context.scene.render.engine="CYCLES"

For change units

bpy.context.scene.unit_settings.system=‘NONE’
bpy.context.scene.unit_settings.system=‘METRIC’
bpy.context.scene.unit_settings.system=‘IMPERIAL’

Greetings.

I was sooo close!)) Thank you very much!