title: Getting type error in python when using for loop
body: <p>I'm sure this will be a very basic question for you, but I'm making a ISBN check digit calculator for my computing class. My current code is this:</p>
  
  <pre><code>isbn = []
  results = []
  
  print("Please input your ISBN 1 number at a time")
  
  def isbn_input():
      isbn.append(int(input("ISBN character 1: ")))
      isbn.append(int(input("ISBN character 2: ")))
      isbn.append(int(input("ISBN character 3: ")))
      isbn.append(int(input("ISBN character 4: ")))
      isbn.append(int(input("ISBN character 5: ")))
      isbn.append(int(input("ISBN character 6: ")))
      isbn.append(int(input("ISBN character 7: ")))
      isbn.append(int(input("ISBN character 8: ")))
      isbn.append(int(input("ISBN character 9: ")))
      isbn.append(int(input("ISBN character 10: ")))
  
  isbn_input()
  
  results.append(isbn[0] * 11)
  results.append(isbn[1] * 10)
  results.append(isbn[2] * 9)
  results.append(isbn[3] * 8)
  results.append(isbn[4] * 7)
  results.append(isbn[5] * 6)
  results.append(isbn[6] * 5)
  results.append(isbn[7] * 4)
  results.append(isbn[8] * 3)
  results.append(isbn[9] * 2)
  
  results = sum(results)
  results = results % 11
  results = 11 - results
  print("Your ISBN is'",
        isbn[0],isbn[1],isbn[2],isbn[3],
        isbn[4],isbn[5],isbn[6],isbn[7],
        isbn[8],isbn[9],results,"'")
  </code></pre>
  
  <p>I know this is an insanely inefficient way of doing it, and you're probably crying even looking at it.</p>
  
  <p>The first thing I did to try making it more efficient is by using a for loop. So, I changed:</p>
  
  <pre><code>def isbn_input():
      isbn.append(int(input("ISBN character 1: ")))
      isbn.append(int(input("ISBN character 2: ")))
      isbn.append(int(input("ISBN character 3: ")))
      isbn.append(int(input("ISBN character 4: ")))
      isbn.append(int(input("ISBN character 5: ")))
      isbn.append(int(input("ISBN character 6: ")))
      isbn.append(int(input("ISBN character 7: ")))
      isbn.append(int(input("ISBN character 8: ")))
      isbn.append(int(input("ISBN character 9: ")))
      isbn.append(int(input("ISBN character 10: ")))
  </code></pre>
  
  <p>to a for list, but I haven't figured out how to do this yet. This is the bit I need help on (Also, I know the function is pointless. Our teacher demanded we have one in, but if anyone can find a better way of doing it then that would be amazing too)</p>
  
  <p>Thanks a lot for the help. Again, if you spot anything which could be made better, then please do. (Also, this is python 3.)</p>