title: Exception: undefined method `blacklisted_keywords'
body: <p>I have the following block of Ruby code within a class:</p>
  
  <pre><code>def self.blacklisted_keywords
    %w(acquista acquistiamo acquisto acquistano compro compriamo comprano)
  end
  
  private
  
  def item_valid?
    keywords = blacklisted_keywords
  end
  </code></pre>
  
  <p>Why can't I call <code>blacklisted_keywords</code> without getting: "undefined method `blacklisted_keywords'"? What am I doing wrong?</p>