title: Insert items from list to another list every n positions
body: <p>I have the following list.</p>
  
  <pre class="lang-python prettyprint-override"><code>vector = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
  inserted_elements = [2, 2, 2, 2, 2]
  </code></pre>
  
  <p>I want to get the following by inserting every two elements.</p>
  
  <pre class="lang-python prettyprint-override"><code>output = [1, 2, 2, 3, 4, 2, 5, 6, 2, 7, 8, 2, 9, 10, 2]
  </code></pre>
  
  <p>Not only the Python list but also the answer using numpy array is fine.</p>