The python dict setdefault method is used to get the value of the item with the specified key. This method actually returns the value of a key (if the key is in a dictionary). If not, it inserts a key with a value to the dictionary.
dictionary.setdefault(keyname, value)
Python dict setdefault example
Simple example code how setdefault() works when the key is in the dictionary.
person = {'name': 'Jack', 'age': 25}
print(person)
age = person.setdefault('age')
print('Age = ', age)
Output:

Another example, if the key is not in the dictionary
person = {'name': 'Jack', 'age': 25}
print(person)
salary = person.setdefault('salary')
print(person)
Output:
{‘name’: ‘Jack’, ‘age’: 25}
{‘name’: ‘Jack’, ‘age’: 25, ‘salary’: None}
Do comment if you have any doubts or suggestions on this Python dictionary function.
Note: IDE: PyCharm 2021.3.3 (Community Edition)
Windows 10
Python 3.10.1
All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.

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