Had an idea on another thread (doctest) about a special exception called "Debug" that could could be raised to generate arbitrary output to stderr.  This would be used instead of spurious print statements in code to inform developers during debugging (which might throw off doctest, for example).  It could also replace "assert" (and improve upon it) which seems to be deprecated.   Also, the __debug__ global could actually gain some functionality...

Its "argument" could be an `eval`uatable string (checked at compile time) and it's output, this very string *plus* the output of it (if it evaluates to something different than itself). 

Just an idea....

mark
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