* issue a warning when Items and Collector form a diamond
addresses #8435
* Apply suggestions from code review
Co-authored-by: Ran Benita <ran@unusedvar.com>
* Return support for the broken File/Item hybrids
* adds deprecation
* ads necessary support code in node construction
* fix incorrect mypy based assertions
* add docs for deprecation of Item/File inheritance
* warn when a non-cooperative ctor is encountered
* use getattr instead of cast to get the class __init__ for legacy ctors
* update documentation references for node inheritance
* clean up file+item inheritance test
enhance docs
move import upwards
Co-authored-by: Ran Benita <ran@unusedvar.com>