How is deterministic encoding performed?

I could not find the code from Equation 6. From my understanding, random noise is being used when encoding the image into noise (https://gitlab.com/cian.unibas.ch/diffusion-anomaly/-/blob/main/guided_diffusion/gaussian_diffusion.py#L565) instead of using the output of the u-net. Where could I find Equation 6 code?