title: singleton classes
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/86582/singleton-how-should-it-be-used">Singleton: How should it be used</a>  </p>
  </blockquote>
  
  
  
  <p>why we should use singleton class</p>