'Deletes the Specified Volume.
For a full list of available parameters, please refer to the official
API reference:
https://developer.openstack.org/api-ref/block-storage/v2/#delete-volume'

def delete_volume(self, volume_id, **params):

    url = ('volumes/%s' % volume_id)
    if params:
        url += ('?%s' % urllib.urlencode(params))
    (resp, body) = self.delete(url)
    self.expected_success(202, resp.status)
    return rest_client.ResponseBody(resp, body)
