Non-existing writeall() reference in Docs

dear julia experts:

writeall still referenced in ‘Avoiding Deadlock in Pipelines’ in the stable docs.

I was looking for a way to have my julia program pass information to an external program via STDIN, and retrieve this program’s STDOUT. But my question is a little broader.

For example, using unix dc as a program, and passing, say, “100 200 + f\n”, reading the result (as long as there is output, here I happen to know it is only one line), then passing “300 - f\n” and reading the result. @async seems the correct way to do this, but it would be simpler to figure out with a working example than with the cryptic mention in the doc.