title: Creating "virtualenv" for an existing project
body: <p>I have a python on which I've been working on. Now I've realized that I need a virtual environment for it. How can I create it <strong>for an existing  project</strong>? If I do this:</p>
  
  <pre><code> virtualenv venv
  </code></pre>
  
  <p>will it work fine? Or do I have to re-create my project, create virtualenv and then copy the existing files to it?</p>