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

given tuple of tuples t:

(('a', 'b')) 

and individual tuple t1:

('a','b') 

why does:

t1 in t 

return false?

update: ipython:

in [22]: t = (('a','b'))  in [23]: t1 = ('a','b')  in [24]: t1 in t out[24]: false 

and how check tuple in tuple?

the problem because t not tuple of tuples, tuple. comma makes tuple, not parentheses. should be:

>>> t = (('a','b'),) >>> t1 = ('a', 'b') >>> t1 in t true 

in fact, can loose outer parentheses:

>>> t = ('a','b'), >>> t1 = 'a','b' >>> type(t) <type 'tuple'> >>> type(t[0]) <type 'tuple'> >>> type(t1) <type 'tuple'> >>> t1 in t true 

although needed precedence, if in doubt put them in. remember, comma makes tuple.