title: Auto create next Key in python dictionary
body: <p>Is there an easy way to create dictionary like associative array in php? in php i can do:</p>
  
  <pre><code>&gt; $x='a';
  &gt; while($x&lt;d){
  &gt;     $arr[]['Letter']=$x;
  &gt;      $x++
  &gt;     }
  </code></pre>
  
  <p>The interpreter adds automatically a new number into empty brackets "[]"
  so i can access letter <code>b</code> from <code>$arr[1]['Letter']</code>, etc.</p>
  
  <p>Is there a way to do same with python?</p>