title: How to specify type parameter
body: <p>How to specify type parameter using sorbet?</p>
  
  <p>For example, I want to annotate a method with an argument of type <code>A</code> returning generic type <code>T[A]</code>.</p>
  
  <pre class="lang-rb prettyprint-override"><code>def build_array(value) 
    [value]
  end
  </code></pre>
  
  <p>The output type depends on the input type: </p>
  
  <pre class="lang-rb prettyprint-override"><code>build_array(42) #=&gt; return Array[Integer]
  build_array('42') #=&gt; return Array[String]
  </code></pre>