Python defaultdict and lambda

Question

In someone else\'s code I read the following two lines:

x = defaultdict(lambda: 0)
y = defaultdict(lambda: defaultdict(lambda: 0))

As the a

Answer 1

All answers are good enough still I am giving the answer to add more info:

"defaultdict requires an argument that is callable. That return result of that callable object is the default value that the dictionary returns when you try to access the dictionary with a key that does not exist."

Here's an example

SAMPLE= {'Age':28, 'Salary':2000}
SAMPLE = defaultdict(lambda:0,SAMPLE)

>>> SAMPLE
defaultdict( at 0x0000000002BF7C88>, {'Salary': 2000, 'Age': 28})

>>> SAMPLE['Age']----> This will return 28
>>> SAMPLE['Phone']----> This will return 0   # you got 0 as output for a non existing key inside SAMPLE