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collections.abc.Iterable don't implement the __bool__ method. This may seriously degrade performance in case __len__ is not efficient.
I suggest to implement it as :
class Iterable:
 ...
 def __bool__(self):
 try:
 next(iter(self))
 return True
 except StopIteration:
 return False

This is as designed. The only method needed for something to qualify as an Iterable is __iter__, thus this is the only method defined on the ABC. If you want your Iterable to be usable in a boolean test, add the __bool__ method to your concrete class.
In fact, you will note that no ABCs define __bool__.
Likewise __len__ is not part of being an Iterator, and in fact in the general case Iterators do not have a len (a given Iterator might be infinite, or it might not be practical to calculate the len).