How do I change the mirror axis?

Hallo everybody.
I have a bit of a problem. I just recently started to use the Python Console for one of my projects. I am importing some .x3d meshes automatically, integrating them into my scene. Well, so for so good.
My actual question is quite simple. I am applying a Mirror Modifier to my imported mesh, which workes just fine.

–> bpy.ops.object.modifier_add(type=‘MIRROR’)

The problem is, that this uses the X-axis to mirro, when I actually need it to use the Z-axis.
I cannot figure out how to do this in my script. …It’s just two mouse clicks in Blender.
Hope anyone can help

Well, that was stupid. After using the Info Window I do realise what I did wrong. :confused: I did try bpy.context.object.modifiers[‘Mirror’].use_z but somehow did not realise that I had to set it True or False. Sorry for this really useless thread.