Was some thought given to providing a mixin for boolean inequalities in total 
orderings (define __le__ and get the rest for free)?

One of the motivating examples in the ABC pep was that the presence of 
__getitem__ was insufficient to distinguish between a sequence and a mapping.  
By registering one of the collections ABCs, a class can make an affirmative 
declaration that it is either a mapping or a sequence.

It seems that there is a similar issue with inequalities.  If something defines 
__le__, you don't necessarily know whether it returns a boolean (it could 
return an array of bools for a vector comparison).  Even if a bool is returned, 
it is not clear whether it implies sortable ordering or whether is something 
with a completely different meaning (i.e. set.issubset).


Raymond
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