 has three independently trained models:
Autoencoder
Conditional Unet
CLIP text encoder
a scheduler component, scheduler, 
a CLIPFeatureExtractor,
as well as a safety checker.
All of these components are necessary to run stable diffusion in inference even though they were trained
or created independently from each other.
To that end, we strive to offer all open-sourced, state-of-the-art diffusion system under a unified API.
More specifically, w