How a weight that was not refreshed this step loses its say: Monty's attention/decay.py.

Attention has to forget, or everything ever looked at stays as interesting as the thing in front of the sensor. A decay is what forgets, and this module holds the one thing the file holds besides its classes: the rate a config means when it says linear and names none.

The decays themselves are Monty.Attention.Decay.NoopDecay and Monty.Attention.Decay.LinearWeightDecay, and what they have in common is Monty.Attention.Decay.VoxelGridWeightDecay.