Reference for composite operations?

[sona1111]

Hi, I know you are likely long done with this project by now, but I thought it was worth a shot. I am working on some similar apis but for other languages. I was wondering if there was a reference implementation anywhere for the composite / blending parameters which were supported in the spec?:

https://www.openraster.org/baseline/layer-stack-spec.html#composite-op-attribute

A reference implementation for how this rendering is being done would be a huge plus, as it seems to be the least straightforward part of the spec.