title: What are underscore names in Kotlin reserved for?
body: <p>In Python you can use <code>_</code> as a variable name. If I write e.g. <code>val _ = 3</code> in Kotlin IntelliJ gives me an error with:</p>
  
  <pre><code>Names _, __, ___, ..., are reserved in Kotlin
  </code></pre>
  
  <p>What are they reserved for? What is their function?</p>