AttributeError: 'Pre_RGB' object has no attribute 'batch_norm'

This error message indicates that there is an attempt to access an attribute called "batch_norm" on an object of type "Pre_RGB", but this attribute does not exist in the object.

To fix this error, you need to check the code where the "Pre_RGB" object is defined and ensure that it has the "batch_norm" attribute defined. If the attribute is missing, you need to add it to the object definition. Alternatively, you may need to modify the code that is trying to access this attribute to use a different attribute that exists in the "Pre_RGB" object.