[m-rev.] for post-commit review: improve comments on stream ops

[Zoltan Somogyi]

For review by Julien.

Zoltan.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: DIFF.sc
Type: application/octet-stream
Size: 3858 bytes
Desc: not available
URL: <http://lists.mercurylang.org/archives/reviews/attachments/20211011/ce27bec3/attachment.obj>