title: Python variable is not being initialized
body: <p>I have the following AWS Lambda function in Python:</p>
  
  <pre><code>def lambda_handler(event, context):
  
      # Code
      # ..
      # ..
      # ..
      # Code
  
      output = ' '
  
      for key in diff.keys():
          for value in diff[key]:
              output += "&lt;br&gt; Key: " + key + ", Value: " + value + "&lt;/br&gt;"
  
      print output
  </code></pre>
  
  <p>Each time i run the function, The value of <code>output</code> is being appended to the value of the previous running, Although it's being initialized with <code>output = ' '</code>.</p>
  
  <p>For example, If the value of <code>output</code> is:</p>
  
  <pre><code>&lt;br&gt; Key: " + A + ", Value: " + 1 + "&lt;/br&gt;
  &lt;br&gt; Key: " + B + ", Value: " + 2 + "&lt;/br&gt;
  </code></pre>
  
  <p>On the next running the value will be:</p>
  
  <pre><code>&lt;br&gt; Key: " + A + ", Value: " + 1 + "&lt;/br&gt;
  &lt;br&gt; Key: " + A + ", Value: " + 1 + "&lt;/br&gt;
  &lt;br&gt; Key: " + B + ", Value: " + 2 + "&lt;/br&gt;
  &lt;br&gt; Key: " + B + ", Value: " + 2 + "&lt;/br&gt;
  </code></pre>
  
  <p>And on the next running it will be:</p>
  
  <pre><code>&lt;br&gt; Key: " + A + ", Value: " + 1 + "&lt;/br&gt;
  &lt;br&gt; Key: " + A + ", Value: " + 1 + "&lt;/br&gt;
  &lt;br&gt; Key: " + A + ", Value: " + 1 + "&lt;/br&gt;
  &lt;br&gt; Key: " + B + ", Value: " + 2 + "&lt;/br&gt;
  &lt;br&gt; Key: " + B + ", Value: " + 2 + "&lt;/br&gt;
  &lt;br&gt; Key: " + B + ", Value: " + 2 + "&lt;/br&gt;
  </code></pre>
  
  <p>What could be the issue?</p>