Eric, right, I left a couple of logical leaps out of my reply as well. My first thought was the same as yours but then I went:

- that means we need to split on commas
- which means we need to track whether or not we're inside a quoted string or not
- which is probably more complexity than is warranted just to produce a slightly better hint to the user

Result: let's just use "<expr>" as a placeholder for "the thing you were trying to print"

Although now that I put it that way, "<output>" is probably a better user-oriented placeholder, since "expr" (short for expression) is a very language-developer-oriented term, while "print(<output>)" is closer to pseudocode.