Why is a tuple of tuples of length 1 not actually a tuple unless I add a comma?

Question

Given a tuple of tuples T:

((\'a\', \'b\'))

and an individual tuple t1:

(\'a\',\'b\')
         


        

Answer 1

Doing this (('a', 'b')) does not make a tuple containing a tuple as you can see here:

>>> T = (('a','b'))
>>> T
('a', 'b')

To make a single element tuple you need to add a trialing comma:

>>> T = (('a','b'),)
>>> t1 in T
True
>>> T
(('a', 'b'),)

In fact the parenthesis aren't even a requirement as this will also create a tuple:

>>> t1 = 'a','b'
>>> t1
('a', 'b')
>>> 1,2,3,4,5,6
(1, 2, 3, 4, 5, 6)