title: Encoding issues with regards to non-alphabet characters
body: <p>I am trying to create an encode function that will take an input such as &quot;Hello!&quot; and produce an encrypted response such as &quot;8.5.12.12.15.999&quot;.  I am struggling with the non-alphabet items such as when I input an exclamation point, i am receiving an error due to my inability to use the '.lower' method.  I am also having trouble with replacing the non-alphabet character with &quot;999&quot;. Any help would be greatly appreciated.</p>
  <pre><code>import string
  
  def encode(saying):
      saying = saying.lower()
      if type(saying) != str:
          return print(&quot;Enter a string&quot;)
      else:
          Dict = dict(zip(string.ascii_lowercase,range(1,27)))
          encode_list = []
          for item in saying:
              encode_list.append(Dict[item])
          output = &quot;.&quot;.join(map(str,encode_list))
          return print(output)
      encode(&quot;Hello&quot;)
  </code></pre>