></h4>
<p>When a stream receives a value, it becomes active (unless the stream is ended).</p>
<pre><code class="lang-javascript">var stream1 = stream(&quot;hello&quot;) // stream1 is active

var stream2 = stream() // stream2 starts off pending
stream2(&quot;world&quot;) // then becomes active
</code></pre>
<p>A dependent stream with multiple parents becomes active if all of its parents are active.</p>
<pre><code class="lang-javascript">var a = stream(&quot;hello&quot;)
var b = stream()

var greeting = strea