title: How can one loop in a ruby with 2 variables on Array
body: <p>In Tcl, if you have a list with even elements, one can loop two elements at a time. See this code:</p>
  
  <pre><code>foreach { a b } [ list 1 2 3 4 ] {
      puts "${a} ${b}"
  }
  </code></pre>
  
  <p>Will output:<br></p>
  
  <pre><code>1 2
  3 4
  </code></pre>
  
  <p>How can one get the same behavior with Ruby?</p>