These two functions are marked interactive-only, yet the docstrings' last
sentence starts "Interactively," which may lead readers to infer that they
can be used non-interactively:

Interactively, N is the prefix arg, and
KILLFLAG is set if N was explicitly specified.

How about the following re-wording for the last sentence:

"A prefix arg becomes N, and sets KILLFLAG."

In fact, this solves another confusion: is pressing C-u "explicitly"
setting N? It might seem not, but it certainly causes KILLFLAG to be set.

If this is satisfactory, I can install a fix.

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