Usage of the “==” operator for three objects

Question

Is there any computational difference between these two methods of checking equality between three objects?

I have two variables: x and y.

Answer 1

Python has chained comparisons, so these two forms are equivalent:

x == y == z
x == y and y == z

except that in the first, y is only evaluated once.

This means you can also write:

0 < x < 10
10 >= z >= 2

etc. You can also write confusing things like:

a < b == c is d   # Don't  do this

Beginners sometimes get tripped up on this:

a < 100 is True   # Definitely don't do this!

which will always be false since it is the same as:

a < 100 and 100 is True   # Now we see the violence inherent in the system!