Your first example isn't what I'd call indentation. "Alignment" maybe. I don't think anyone would expect that to work in a proportional font.

For the second one, I'd write it this way.

def foo(

....arg1,

....arg2,

....arg3)

I prefer that even in a fixed width font.

This still matches the parent's picture

> If you use spaces to indent code, or in any way rely on a fixed width font to "line things up", you have a fundamental misunderstanding.

As long as the limitations of lining things up "exactly" are avoided, spaces shouldn't be any different than whatever way comes from true understanding.

I do use spaces to indent code. And I still have no idea what my fundamental misunderstanding is supposed to be.

My take on it is that (most) code isn't a picture, so drawing with it (alignment especially) is missing the point that code is a form of text instructions.

If anything, the editor should "render" the text in a form that is pleasant to the eye, divorcing the meaning from the presentation.

Lining up things too much is a "works for me" way of baking presentation into the data, where the writer assumes that because it looks good o their setup, it will look well for the reader too.

Similarities can be seen to building web pages on tables, sending around Word documents, or hard-wrapping emails.