title: How can I combine two Arrays with the arguments Arrays into one Array in Kotlin?
body: <p>I want to make one array from two arrays.</p>
  
  <pre><code>var a1 = arrayOf(1, 2, 3)
  var a2 = arrayOf(4, arrayOf(5,6), 7)
  
  var a3 = a1 + a2
  </code></pre>
  
  <p>But I get a compile error:</p>
  
  <pre><code>None of the following functions can be called with the arguments supplied:
  public operator fun &lt;T&gt; Array&lt;???&gt;.plus(element: ???): Array&lt;???&gt; defined 
  in kotlin.collections
  public operator fun &lt;T&gt; Array&lt;???&gt;.plus(elements: Array&lt;out ???&gt;): 
  Array&lt;???&gt; defined in kotlin.collections
  public operator fun &lt;T&gt; Array&lt;Int&gt;.plus(elements: Collection&lt;Int&gt;): 
  Array&lt;Int&gt; defined in kotlin.collections
  </code></pre>
  
  <p>How can I combine them?</p>