title: How to use params.fetch strong parameters
body: <p>When using <code>rails g scaffold kittens</code> the strong parameters function, <code>kitten_params</code> is</p>
  
  <pre><code>def kitten_params
    params.fetch(:kitten, {})
  end
  </code></pre>
  
  <p>I am familiar with strong parameters, 
  <code>params.require(:kitten).permit(:name, :age)</code>
   but I'm not sure how to use the <code>fetch</code> method for this.</p>