"Can't instantiate abstract class Instance_Segmentation_Model with abstract method forward"

[Geson12138]

I run the command "sh demo.sh", and an error occurred:

<hydra.errors.InstantiationException: Error in call to target 'model.detector.Instance_Segmentation_Model':
TypeError("Can't instantiate abstract class Instance_Segmentation_Model with abstract method forward")>

I found that "class Instance_Segmentation_Model(pl.LightningModule):" in model.detector.py
It seems that there is an abstract method "forward()" in the class "pl.LightningModule", which needs to be defined when instantiating it.

So I want to know how to solve this problem？ Thank you