l data events
of the stream it transforms are actually instances of <code>S</code>,
and it will check that all data events produced by this transformer
are actually instances of <code>RT</code>.</p>
    </section>
    
    <section class="summary source-code" id="source">
      <h2><span>Implementation</span></h2>
      <pre class="language-dart"><code class="language-dart">StreamTransformer&lt;RS, RT&gt; cast&lt;RS, RT&gt;() =&gt;
    StreamTransformer.castFrom&lt;S, T, RS, RT&gt;(this);</code></pre>
    <