Blossom project in computer science course

from linked_list import Node, LinkedList
from blossom_lib import flower_definitions
class HashMap:
  def __init__(self,size):
    self.array_size = size
    #self.array = [None for i in range(size)]
    self.array = [LinkedList() for i in range(size)]

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

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

  def assign(self,key,value):
    array_index = self.compress(self.hash(key))  
    #self.array[array_index] = [key,value]
    payload = Node([key,value])
    list_at_array = self.array[array_index]
    for item in list_at_array:
      if key == item[0]:
         item[1] = value
         return
    list_at_array.insert(payload)

  def retrieve(self,key):
    array_index = self.compress(self.hash(key))
    #payload = self.array[array_index]
    list_at_index = self.array[array_index]
    for item in list_at_index:
      if key == item[0]:
        return item[1]
    return None
    #if payload is not None and payload[0]== key:
      #return payload[1]
    #else:
      #return None
    #if payload is None:
      #return None

    #if payload[0] != key:
      #return None

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

I implemented the code according to the instructions and also went through the unstuck video, but while printing the output, the values looked like this:-

None
None
None
None
None
None
None
None
None
None
None
None
None
good luck