title: Self made variable not working in python
body: <p>Hey everyone i'm abit of a noob when it comes to python and i was playing around with an unfinished mark to grade converter i had started in class. Everything works fine up until 'if second == yes:' where it says that yes in undefined. How do i solve this?!?!?! Again i'm a noob and i thought that this website would be the easiest place to get an answer(aside from school but i cba). Thanks for any help!</p>
  
  <pre><code>print("-------WELCOME-------")
  
  testscore = int(input("What mark did you get?"))
  
  if testscore&gt; 75:
      print("You got an A!")
  else:
      if testscore&lt; 30:
          print("You got an F")
  
  second = input("do you want to get another test score?")
  if second == yes:
      if testscore&gt; 75:
          print("You got an A!")
  else:
      if testscore&lt; 30:
          print("You got an F")
  if second == no:
      print("Thanks for using MARK TO GRADE CONVERTER. See you soon!")
  </code></pre>