[BUG] Handle case when labels=None in Triangle.drop()

[genedan]

Are you on the latest chainladder version?

• Yes, this bug occurs on the latest version.

Describe the bug in words

The signature of Triangle.drop() has the default argument labels=None. However, this results in a TypeError when used in combination with the only (currently) supported axis=1.

How can the bug be reproduced?

import chainladder as cl
raa = cl.load_sample('raa')

raa.drop(axis=1)

...
TypeError: 'NoneType' object is not iterable

What is the expected behavior?

The case when labels=None is meant to accommodate the situation when index, columns, origin, or development parameters are used instead. These have yet to be implemented, so this issue should be solved only after those parameters have been implemented.

When none of labels, index, columns, origin, or development are filled out, we should receive the following error message:

raa.drop()
...
ValueError: Need to specify at least one of 'labels', 'index', 'columns', 'origin', or 'development'

Would you be willing to contribute this ticket?

• Yes, absolutely!
• Yes, but I would like some help.
• No.