title: What does << mean in groovy
body: <p>I am trying to read some groovy and came across the "double less than" <code>&lt;&lt;</code> in a couple contexts.  It is hard to google.  How does it work in these examples?</p>
  
  <pre><code>new URL('the url').withInputStream{ i -&gt; f.withOutputStream{ it &lt;&lt; i }}
  </code></pre>
  
  <p>and in Gradle:</p>
  
  <pre><code>task hello &lt;&lt; {
    println 'Hello world!'
  }
  </code></pre>