The membership operator in checks if the key is present in the dictionary and returns True, else it returns False.
>>> dict1 = {'Mohan':95,'Ram':89,'Suhel':92,
'Sangeeta':85}
>>> 'Suhel' in dict1
True
The not in operator returns. True if the key is not present in the dictionary, else it returns False.
>>> dict1 = {'Mohan':95,'Ram':89,'Suhel':92,
'Sangeeta':85}
>>> 'Suhel' not in dict1
False