title: IndexError: list index out of range - for i in arr1 and arr2
body: <p>You are presented with two arrays, all containing positive integers. One of the arrays will have one extra number, see below:</p>
  
  <p><code>[1,2,3]</code> and <code>[1,2,3,4]</code> should return <code>4</code></p>
  
  <p><code>[4,66,7]</code> and <code>[66,77,7,4]</code> should return <code>77</code></p>
  
  <p>My code:</p>
  
  <pre><code>def find_missing(arr1, arr2):  
    if len(arr1) != len(arr2):  
      for i in arr1 and arr2:  
          if arr1[i] != arr2[i]:  
            return i
  </code></pre>
  
  <p>Is producing this error:</p>
  
  <pre><code>Traceback (most recent call last): File "python", line 1, 
  in &lt;module&gt; File "python", line 4, in find_missing 
  IndexError: list index out of range
  </code></pre>