New concept (objects) and exercise for review

I just noticed that some “proper terms” are in quotes while others are italicized or even bold.

The parameter to del is an index expression
If you cannot refer to the key as an identifier, use bracket notation.
It is valid to use keys that are not “identifier-like”.

Do we want to make these consistent?

I think I was trying to bold a term the first time I used it, and italics to re-use a term.

I’ve read it too many times to catch these small details, so I’d appreciate edits.