Find the error in the following code fragment box = {} jars = {}

Q. Find the error in the following code fragment. State the reason behind the error.

box = {}

jars = {}

crates = {}

box['biscuit'] = 1

box['cake' ] = 3

jars['jam'] = 4

crates['box'] = box

crates['jars'] = jars

print (crates [box])

Answer :-

The above code will produce error with print() because it is trying to print the value from dictionary crates by specify a key which is of a mutable type dictionary(box is a dictionary). There can never be a key of mutable type in a dictionary, hence the error.
The above code can be corrected by changing the print() as :

print (crates['box']).


Example :-

box = {}
jars = {}
crates = {}
box['biscuit'] = 1
box['cake' ] = 3
jars['jam'] = 4
crates['box'] = box
crates['jars'] = jars
print (crates ['box'])

Output :-

{'biscuit': 1, 'cake': 3}
>>>