d11.py

from collections import defaultdict

#default_factory is mentioned as 'int' class.

d=defaultdict(int)
d['a']=1
d['b']=2
#default_factory attribute is int class.
print (d)#Output:defaultdict(<class 'int'>, {'a': 1, 'b': 2})


print (d.get('a'))#Output:1
#get() method -> will return None, if key doesn't exists. __missing__() is not called.
print (d.get('z'))#Output:None


#In regular dictionary
d1={'a':1,'b':2}
#get() method -> returns None , if key doesn't exists.
print (d1.get('a'))#Output:1
print (d1.get('z'))#Output:None