title: Prolog - Counting specific elements in list of lists
body: <p>I have a list 'a' in Prolog.</p>
  
  <pre><code>a = [].
  </code></pre>
  
  <p>I have to insert to 'a' another list 'b'</p>
  
  <pre><code>b = [bottle].
  </code></pre>
  
  <p>The final result has to be like this: </p>
  
  <pre><code>a = [[bottle]].
  </code></pre>
  
  <p>The build-in function <em>append/3</em> seems to only concatenate two lists.</p>
  
  <p><code>append([item1,item2],[item3,item4],Ans)</code> gives us <code>Ans = [item1,item2,item3,item4]</code> but I need </p>
  
  <pre><code>Ans = [[1,2,3],[4,5,6]].`
  </code></pre>
  
  <p>Can you please help me with this task, I am completely noob in prolog. </p>