title: Where should I put a custom method for a existing class in rails?
body: <p>I want to add a method <code>nil_or_zero?</code> to <code>Object</code> class in my Rails project.</p>
  
  <pre><code>class Object
     def nil_or_zero?
       self.nil? or self == 0
     end
  end
  </code></pre>
  
  <p>Where should I put the file for it?
  And what name is preferable in rails culture?</p>