title: TypeError (unorderable types: int() <= NoneType())
body: <p>This is my first time writing code in Python and could use some help. I am using Python 34 and simply cannot understand what is going on.       </p>
  
  <pre><code>def roll(v):
      x = input()
      return (x + v)
  
  def startGame():
      v = 0
      while 0 &lt;= v: # error points to this line
          v = roll(v)  
  
  print("Thanks for playing")
  </code></pre>
  
  <p>I declare v to be an integer with a  value of 0. But when I try to compare it to another integer, it gives me the  error message <code>unorderable types: int() &lt;= NoneType()</code>
  I could use some guidance..
  Thanks</p>