title: How can I add a tag to a key in boto (Amazon S3)?
body: <p>I am trying to tag a key that I've uploaded to S3. In the same below I just create a file from a string. Once I have they key, I'm not sure how to tag the file. I've tried Tag as well as TagSet.</p>
  
  <pre><code>from boto.s3.bucket import Bucket
  from boto.s3.key import Key
  from boto.s3.tagging import Tag, TagSet
  
  k = Key(bucket)
  k.key = 'foobar/somefilename'
  k.set_contents_from_string('some data in file')
  
  Tag(k, 'the_tag')
  </code></pre>