why (a and b) different from (b and a)

[bowlofred]

From the Python Documentation

x and y --- if x is false, then x, else y

In other words, whenever the first item in an and is true, return the second item.

So for your tuples a and b, are they false or true?

By default, an object is considered true unless its class defines either a __bool__() method that returns False or a __len__() method that returns zero, when called with the object. 1 Here are most of the built-in objects considered false:

• constants defined to be false: None and False.
  
• zero of any numeric type: 0, 0.0, 0j, Decimal(0), Fraction(0, 1)
  
• empty sequences and collections: '', (), [], {}, set(), range(0)

Since neither of your tuples are empty, they are both evaluated as true. That means you'll always see the second item returned.

>>> 1 and 2
2
>>> 2 and 1
1