title: Use Bisection Search to guess number
body: <p>I'm writing a program that is supposed to guess the user's secret number using bisection search. I feel like I understand the concept of bisection search quite well but my IDE (Canopy) won't let me 'run' the code, which I assume is due to an error or something that it wants me to do before I run it.</p>
  
  <pre><code>lowend = 1
  highend = 100
  guess = 50
  choice = 0
  
  print "Please think of a number between 0 and 100!"
  
  while choice != 'c':
      print "Is your secret number " + str(guess) + "?"
      print "Enter 'h' to indicate the guess is too high.",
      print "Enter 'l' to indicate the guess is too low.",
      choice = raw_input("Enter 'c' to indicate I guessed correctly.")
      if choice == 'c':
          break
      elif choice == 'h':
              highend = guess
              guess = (highend + lowend)/2
              print 'Is your secret number ' + str(guess) + "?"
              choice = 0
      elif choice == 'l':
              lowend = guess + 1
              guess = (highend + lowend)/2
              print 'Is your secret number ' + str(guess) + "?"
      else:
              print "Sorry, I did not understand your input."
              choice = 0
  
  print 'Your number is: ' + str(guess) + "."
  </code></pre>
  
  <p>I'm not sure if there's something I'm doing wrong, but Canopy's green 'run' button is greyed out. Why does this happen? Does anyone see anything obviously wrong with my code?</p>