title: Translating date to day of week
body: <p>I have a method to translate naming days of week to my native language:</p>
  
  <pre><code>def translate_date(daytime)
    case daytime
    when daytime.strftime('%A') == 'Monday'
      'Poniedziałek'
    when daytime.strftime('%A') == 'Tuesday'
      'Wtorek'
    when daytime.strftime('%A') == 'Wednesday'
       'Środa'
    when daytime.strftime('%A') == 'Thursday'
       'Czwartek'
    when daytime.strftime('%A') == 'Friday'
       'Piątek'
    when daytime.strftime('%A') == 'Saturday'
       'Sobota'
    when daytime.strftime('%A') == 'Sunday'
       'Niedziela'
    end
  end
  </code></pre>
  
  <p>I use it for example as:</p>
  
  <pre><code>date = Sat, 21 May 2016 00:00:00 UTC +00:00
  translate_date(date) # =&gt; nil
  </code></pre>
  
  <p>Where is the problem with this method? Why does it return <code>nil</code>?</p>
  
  <p>Meanwhile, I get:</p>
  
  <pre><code>date.strftime('%A') == 'Saturday' # =&gt; true`
  </code></pre>