Actually David I didn’t notice your suggested wording <https://bugs.python.org/issue20344#msg214364> before. Adding that last sentence, pointing to the full description of the Popen constructor, would be fine.

My complaint about mentioning “iterable” is that iterables are not mentioned anywhere else in the documentation. I would rather leave it out or change it to “sequence”, unless the rest of the documentation is made consistent, e.g. “args . . . should be a string, or a sequence of program arguments” would also need fixing.