[m-rev.] diff: factor out common code in inst_check.m

[Zoltan Somogyi]

This should not need review.

Zoltan.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Log.ic
Type: application/octet-stream
Size: 398 bytes
Desc: not available
URL: <http://lists.mercurylang.org/archives/reviews/attachments/20230529/75ca0d02/attachment-0002.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: DIFF.ic
Type: application/octet-stream
Size: 9013 bytes
Desc: not available
URL: <http://lists.mercurylang.org/archives/reviews/attachments/20230529/75ca0d02/attachment-0003.obj>