def clean_semver(cls, version_spec):
        return re.sub(r"([<>=~])\s+?v?", "\\1", version_spec, re.IGNORECASE)
def list_snapshots(self, params=None):
        """List all the snapshot."""
        url = 'snapshots'
        if params:
                url += '?%s' % urllib.urlencode(params)

        resp, body = self.get(url)
        body = json.loads(body)
        return resp, body['snapshots']