title: Raise class exception or instance of class exception when no arguments are passed
body: <p>I saw that sometimes there are raised classes and sometimes there are raised instances of classes.</p>
  
  <p>Which way to raise exception is better if you don't want to add any additional info as arguments</p>
  
  <pre><code>raise ValueError
  </code></pre>
  
  <p>or</p>
  
  <pre><code>raise ValueError()
  </code></pre>
  
  <p>?</p>