# FAQ: Hash Maps: Python - Review

#1

This community-built FAQ covers the “Review” exercise from the lesson “Hash Maps: Python”.

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This exercise can be found in the following Codecademy content:

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#2

Hello!

I was just copying down the code in my notes and found something that I don’t understand.

def retrieve(self, key):
array_index = self.compressor(self.hash(key))
possible_return_value = self.array[array_index]

``````if possible_return_value is None:
return None

if possible_return_value[0] == key:
return possible_return_value[1]

retrieval_collisions = 1

while (possible_return_value != key):
new_hash_code = self.hash(key, retrieval_collisions)
retrieving_array_index = self.compressor(new_hash_code)
possible_return_value = self.array[retrieving_array_index]

if possible_return_value is None:
return None

if possible_return_value[0] == key:
return possible_return_value[1]

number_collisions += 1

return
``````

This is the retrieval method but it ends with += 1 for number_collisions and not retrieval_collisions. This is the solution that Codecademy gives, so I think it must be right, only I don’t understand why we +1 number_collisions which is in the Assign method. Can anyone explain? Thanks!

#3

i think so it’s a typo, the correct solution would be retrieval_collisions+=1