title: 'builtin_function_or_method' object is not subscriptable
body: <pre><code>def binary_search(li, targetValue):
      low, high = 0, len[li] #error on this line
      while low &lt;= high:
          mid = (high - low)/2
          if li[mid] == targetValue:
               return "we found it!"
          elif li[mid] &gt; targetValue:
               low = mid - 1;
          elif li[mid] &lt; targetValue:
               high = mid + 1;
      print "search failure "
  </code></pre>
  
  <p>just posted this question recently, but my code still doesn't work? </p>