title: Erlang compound boolean expression
body: <p>I read the documentation about using <code>and</code>, <code>or</code> operators, but why is the following not evaluating?</p>
  
  <pre><code>X = 15,
  Y = 20,
  X==15 and Y==20.
  </code></pre>
  
  <p>I am expecting for a "true" in the terminal, but I get a "syntax error before ==".</p>