title: Fatal: destination path 'opencv_contrib' already exists and is not an empty directory
body: <p>So I tried to get opencv_contrib using : </p>
  
  <blockquote>
    <p>$ git clone <a href="https://github.com/Itseez/opencv_contrib" rel="nofollow noreferrer">https://github.com/Itseez/opencv_contrib</a></p>
  </blockquote>
  
  <p>Which gave me the following error :</p>
  
  <blockquote>
    <p>fatal: destination path 'opencv_contrib' already exists and is not an empty directory.</p>
  </blockquote>
  
  <p>I tried to check the directory contents :</p>
  
  <blockquote>
    <p>$ ls -a</p>
  </blockquote>
  
  <p>And this is what I got : </p>
  
  <p><a href="https://i.stack.imgur.com/eScTZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/eScTZ.png" alt="screenshot"></a></p>
  
  <p>Being new to all this, I really am unable to understand what's wrong and what needs to be done. Mainly I need to know how do I make the required directory empty so I can continue with the installation.</p>