title: Does double less than minus "<<-" sign mean anything in ruby?
body: <p>I am trying to get myself familiar with ruby syntax and coding styles(i am a newbie). I came across a code that uses <code>&lt;&lt;-</code>, what does this mean in Ruby? Code is</p>
  
  <pre><code>  def expectation_message(expectation)
      &lt;&lt;-FE
        #{expectation.message}
        #{expectation.stack}
      FE
    end
  </code></pre>
  
  <p>This is just a section of the whole code. Any help would be appreciated.</p>