exr metada with python

Trying to add exr metadata with python. Dont really know how but tried as the example below and got an error

import hou

hou.parm(‘/out/vray/SettingsEXR_extra_attributes’).set(“test=1;”)
.png.png

It’s the same in Mantra.
That’s what I’ve found: https://houdinitricks.com/pre-post-render-python-scripts-mantra/
You need to use “execfile(”/path/to/file.py")".

ah! should have tried that, thanks!