Convenience method to retrieve a specific keypair (KeyPair).

        :type image_id: string
        :param image_id: the ID of the Image to retrieve

        :rtype: :class:`boto.ec2.keypair.KeyPair`
        :return: The KeyPair specified or None if it is not found

def get_key_pair(self, keyname):
        """
        Convenience method to retrieve a specific keypair (KeyPair).

        :type image_id: string
        :param image_id: the ID of the Image to retrieve

        :rtype: :class:`boto.ec2.keypair.KeyPair`
        :return: The KeyPair specified or None if it is not found
        """
        try:
            return self.get_all_key_pairs(keynames=[keyname])[0]
        except self.ResponseError, e:
            if e.code == 'InvalidKeyPair.NotFound':
                return None
            else:
                raise