title: What is the format of string literal @ in yaml format?
body: <p>I have a hash table of twitter users.</p>
  
  <pre><code>tweeter1: @jack
  tweeter2: @jill
  tweeter3: @john
  </code></pre>
  
  <p>But because of <code>@</code>, I can't <code>YAML.load</code> the file.</p>
  
  <p>The error it throws is <code>Psych::SyntaxError: (&lt;unknown&gt;): did not find expected node content while parsing a flow node at line 1 column 11</code></p>
  
  <p>How do you use string literal for <code>@</code> in YAML?</p>