title: How to omit lambda parameters in Kotlin?
body: <p>Sometimes I don't use all lambda parameters, like the second parameter in the example below, which is an old value in a change event:</p>
  
  <pre><code>selected.onChange { value, _ -&gt;
      checkBox.isChecked = value
  }
  </code></pre>
  
  <p>How do I omit them? Cause that clutters the code and hurts readability. Previously I used the method above, but in kotlin 1.0.0-beta-1103 underscores are reserved.</p>