How do I set {argslist} programmatically in vim?

I know I can set the list of files like this:

:args file1.txt file2.txt file3.txt

I would like to set args based on a command. I also know, if I used a fresh vim, I could do this:

vim $(some-command)

What I want to do is something like this:

:argsexpr system('some-command')

Like how :cexpr and :lexpr work.

Ideas?

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