def lookup(self, key_name, headers=None, callback=None):
        """
        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.
        """
        return self.get_key(key_name, headers=headers, callback=callback)