Where is the forward() function of the mask rcnn?

This seems really silly but where is the forward() function of the mask rcnn? I have been looking through https://github.com/pytorch/vision/blob/2831f11abcb9ec7b951b6bbbcb7a85b79ee2fd79/torchvision/models/detection/mask_rcnn.py but can’t find it at all.

I am trying to modify the mask rcnn’s forward pass https://pytorch.org/docs/stable/torchvision/models.html#torchvision.models.detection.maskrcnn_resnet50_fpn


It is inherited from its parent class.
So all the way to this class: https://github.com/pytorch/vision/blob/2831f11abcb9ec7b951b6bbbcb7a85b79ee2fd79/torchvision/models/detection/generalized_rcnn.py#L15