Hash map using separate chaining to avoid collisions in Python

hash_table_blossom.py

from linked_list_for_hash import Node, LinkedList
from blossom_lib import flower_definitions


class HashMap:
    def __init__(self, size):
        self.array_size = size
        self.array = [LinkedList() for i in range(size)]

    def hash(self, key):
        return sum(key.encode())

    def compress(self, hash_code):
        return hash_code % self.array_size

    def assign(self, key, value):
        hash_code = self.hash(key)
        array_index = self.compress(hash_code)

        payload = Node([key, value])
        list_at_array = self.array[array_index]
        for item in list_at_array:
            if item[0] == key:
                item[1] = value
        list_at_array.insert(payload)

    def retrieve(self, key):
        hash_code = self.hash(key)
        array_index = self.compress(hash_code)

        list_at_index = self.array[array_index]
        for item in list_at_index:
            if item[0] == key:
                return item[1]
        return None


blossom = HashMap(len(flower_definitions))
for flower in flower_definitions:
    blossom.assign(flower[0], flower[1])

print(blossom.retrieve('daisy'))