code: def lookup(self, key_name, headers=None, callback=None):
          
          return self.get_key(key_name, headers=headers, callback=callback)
docs: Deprecated: Please use get_key method.
          
          :type key_name: string
          :param key_name: The name of the key to retrieve
          
          :rtype: :class:`boto.s3.key.Key`
          :returns: A Key object from this bucket.