simultaneous assignment

[Terry Reedy]

"John Salerno" <johnjsal at NOSPAMgmail.com> wrote in message 
news:tsM5g.2033$No6.43913 at news.tufts.edu...
> I'm sure it's not necessary. Basically W, X, Y and Z are propositions
> that are either true or false, and the puzzle lists a few statements
> such as "Exactly one of X, Y and Z is true", and I'm trying to work out
> a little algorithm that might test for this kind of stuff.

X+Y+Z == 1 # or bool(X)... if not booleam

> Another thing I'm trying to do is write a function that tests to see if
> a list contains exactly one true item, and the rest are false (obviously
> this would have to be a list of boolean values, I guess). I'm sure this
> isn't a handy utility, but I enjoy figuring out how to implement it.

Use sum().  Being able to count true values by adding is a reason bool is a 
subclass of int.

Terry Jan Reedy