Example:
https://dlang.org/library/std/algorithm/iteration/each.each.html
isForeachIterable and isRangeIterable are private and rather complex. They are neither documented, nor accessible to user code. The user's only chance is peruse the source code or "build and pray".
All constraints on public-visible code should have public visibility.
Comment #1 by robert.schadek — 2024-12-01T16:37:38Z