help me

[zrt791521360]

pytorch-drl4vrp/tasks/vrp.py

Line 127 in 5b9b86e

all_demands[visit_idx, 0] = -1. + new_load[visit_idx].view(-1)

HELLO，thanks for your solid work.
Why does the demand for depot need to be reduced? Can you tell me the practical significance and function of this line of code.