title: Using a case/when checking a negative number
body: <pre><code>number = -5
  
  case number
  when number &lt; 0
    return "Please enter a number greater than 0."
  when 0..1
    return false
  when 2
    return true
  end
  ...
  </code></pre>
  
  <p>I expected it to return "Please enter a number greater than 0", but instead it returned nil.  Why is that? How can I check if the number is less than 0? </p>