Changing active cameras to get view by script

Hi there.

I have multiple cameras in the scene with different objects. I want to change from one camera to the another one to make that them active one by one so that i can render the scene from different views.

Simply using command(where obj is corresponding camera) does noes not work. In GUI, i know that being in 3D view we can select that camera and make it active by Ctrl+numpad0.

But i can not do it using script. As far as i understood i may need to play with bl_space_type and bl_region_type. I am newly using blender,i need a help with this issue.