Should each list in adjacency lists be terminated by -1?

[PatrickOHara]

• TSPLIB 95 version: 0.7.1
• Python version: 3.8
• Operating System: Mac OS X

Description

In test_adjacency_list_fields.py, the end of each list is terminated by -1:

    return '\n'.join([
        '0 1 2 3 -1',
        '1 0 2 3 -1',
        '2 0 1 3 -1',
        '3 0 1 2 -1',
        '-1',
    ])

But in test_edge_data_field.py there is only \n separating each adj list.

Which is correct?

Terminating each list with a -1 means an adjacency cannot be accidently interpreted as an edge list, removing any ambiguity. This seems cleaner?