About the Implementation of Classifier-Free Guidance

[jsttlgdkycy]

https://github.com/hpcaitech/Open-Sora/blob/2361353844da516bc711720c0cd82989e1467769/opensora/schedulers/iddpm/init.py#L91 Since there are four channels in the latent space, I wonder why only the first three channels are selected to apply CFG. Is this a typo or something else? Could someone tell me about this? I will be very appericated.