title: `to_s` isn't converting an integer to a string
body: <p>I am calling <code>to_s</code> within a method:</p>
  
  <pre><code>$  def my_function(num)
  $    number = num.to_s.split(//)
  $    puts number
  $  end
  
  $  my_function(233)
  2
  3
  3
  # =&gt; nil
  </code></pre>
  
  <p>It looks to me like within the function, no array is created since the output is <code>nil</code>. Why is an array of strings not created when <code>to_s.split(//)</code> is called inside a method?</p>
  
  <p>Also, why is the output for <code>puts number</code> seemingly just each digit on its own line? Do I need to explicitly create the array within the function and then explicitly push the split number into it?</p>