Getting an IndexError: string index out of range
<p>I'm not sure why I'm getting an </p>

<blockquote>
  <p>IndexError: string index out of range </p>
</blockquote>

<p>with this code. </p>

<pre><code>s = 'oobbobobo'
a = 0
for b in range(len(s)-1):
    if (s[b] == 'b') and (s[b+1] == 'o') and (s[b+2] == s[b]):
        a += 1
    elif (s[b] == 'b') and (s[b+1] == 'o') and None:
        break 

print("Number of times bob occurs is: ", a)
</code></pre>

<p>I thought the <code>elif</code> statement would fix the error, so I'm lost.</p>