Python blackjack program code issue. Why is it returning key "1" instead of "10"?

I used python tutor to step through the code and found that there is a bug in user_current_score(). for cards.get(card), it is pulling the "10" dictionary key but seeing it as a 1 instead, then returning None since there is no 1 card. Why would it be seeing a 1 card in the dictionary when there isn’t one there? I know I could do this differently, but I still want to know why it’s pulling the "10" key as a "1" instead and returning "None". If I comment the "10" dictionary key value pair out, there’s no problem with the code so far. If it pulls a 10 though, I get this error:

10
 
None
Traceback (most recent call last):
  File "main.py", line 146, in <module>
    user_current_score()
  File "main.py", line 133, in user_current_score
    user_score += cards.get(card)
TypeError: unsupported operand type(s) for +=: 'int' and 'NoneType'

or

K
10
 
10
None
Traceback (most recent call last):
  File "main.py", line 146, in <module>
    user_current_score()
  File "main.py", line 133, in user_current_score
    user_score += cards.get(card)
TypeError: unsupported operand type(s) for +=: 'int' and 'NoneType'
 

Code:

import random
cards = {
  "A":11,
  "2":2,
  "3":3,
  "4":4,
  "5":5,
  "6":6,
  "7":7,
  "8":8,
  "9":9,
  "10":10,
  "J":10,
  "Q":10,
  "K":10
}
user_hand = []

comp_hand = []
comp_score = 0
temp_hand = []
translation = {39: None}

def deal_card():
  temp_hand = []
  temp_hand = random.choice(list(cards))
  print(temp_hand) #for testing, needs removed
  return temp_hand

def user_current_score():
  user_score = 0
  for card in user_hand:
    print(cards.get(card))  #for testing, needs removed
    user_score += cards.get(card)
  print("Your cards:", str(user_hand).translate(translation) + f", current score: {user_score}")
  return user_score

def comp_current_score():
  comp_score = 0
  for card in comp_hand:
    comp_score += cards.get(card)
  return comp_score  

while len(user_hand) < 5:
  user_hand += deal_card() 
print(" ")
user_current_score()

>Solution :

You should use append method to add values to your lists.

When you try to += list with str (with more than 1 character) you are actually splitting this str to characters and append them sequentally.

try this one:

while len(user_hand) < 5:
  user_hand.append(deal_card())