title: Python yield returns characters instead of string from single-element tuple
body: <p>I'm using <code>yield</code> to process each element of a list. However, if the tuple only has a single string element, <code>yield</code> returns the characters of the string, instead of the whole string:</p>
  
  <pre><code>self.commands = ("command1")
  ...
  for command in self.commands:
          yield command            # returns 'c' not 'command1'
  </code></pre>
  
  <p>how can i fix this?</p>
  
  <p>Thanks</p>