def __init__(self, package, version):
        """Construct a new requirement.

        :param package: the package name.
        :param version: a semver compatible version specification.
        """
        self.package = package
        self.version = version
        if self.version and not re.match(r"[<=>~]", version[:2]):
            self.version = "=={}".format(self.version)
def update_snapshot_metadata(self, snapshot_id, metadata):
        """Update metadata for the snapshot."""
        put_body = json.dumps({'metadata': metadata})
        url = "snapshots/%s/metadata" % str(snapshot_id)
        resp, body = self.put(url, put_body)
        body = json.loads(body)
        return resp, body['metadata']