title: randint returns same number over and over
body: <p>I'm just getting started with Python, and ran into a problem. I'm writing a function to simulate a coin flip. 
  When I wrote some mock code to test the randint function it worked perfectly fine and returned a nice random sequence of heads and tails. The code I try to use in my program however returns only h's or t's. </p>
  
  <pre><code>import random
  
  coin_sequence = "hhththththhhhttthht"
  generated_sequence = "" #define generated_sequence
  length = len(coin_sequence)
  flip = random.randint(0, 1)
  for value in range(length):
      if flip == 0:
          generated_sequence = generated_sequence + "t"
      else:
          generated_sequence = generated_sequence + "h"
  
  print(generated_sequence)
  </code></pre>
  
  <p>I probably made some really stupid mistake. Who can help me? </p>