Q:

How can i enable composite node in python? 

though with the codes i have searched in google , it still doesn't solve the problem, i want to enable one specific composite node like this :

and this is the inactive state:

From inactive state to active state , there is only such script indicated in Google 
scene = bpy.context.scene
compositing_node_tree = scene.node_tree
compositing_node_tree.nodes['os_composite'].select = True

But it just functions select node rather than enable node :

How can i enable this specific composite node in python? 
Thanks if you have any ideas! 

A:

Set active node
Similarly to Set active image node with python
In the python console 
C = bpy.context
D = bpy.data

>>> node = C.scene.node_tree.nodes['Composite']
>>> node.select = True
>>> C.scene.node_tree.nodes.active = node
>>> 

