Help Understanding and Modifying CVRP_Reload

[codebytesfl]

Hello I'm trying to figure out and logically understand how to use OR-tools to solve a CVRPTW problem but with the ability for a vehicle to go back to a depot to unload, and MAYBE pick up another item to deliver.

The idea is we have a truck that delivers construction garbage dumps. We have 1 depot where we store garbage dumps. Some may be full (cannot be picked up for a delivery) some may be empty (can be picked up for a delivery). Each day we have a list of deliveries (clients who need an empty dump) and pickups (clients who need a full dump picked up).

The truck can only carry 2 dumps at a time, so therefore if a truck picks up two full dumps, it will need to head back to the depot to unload. If there are more deliveries to be made the truck can "reload" and pick up more empty dumps. For now we can assume there will be an unlimited amount of empty dumps at the depot ready for pickup that can be used to supply any delivery.

I feel like the cvrp_reload.py example is extremely close to what I need, but I cannot tell if it is unloading when the truck is 'at capacity', and picking more 'empty' dumps up.