'Update specified extra Specs of the mentioned flavor and key.
For a full list of available parameters, please refer to the official
API reference:
https://developer.openstack.org/api-ref/compute/#update-an-extra-spec-for-a-flavor'

def update_flavor_extra_spec(self, flavor_id, key, **kwargs):

    (resp, body) = self.put(('flavors/%s/os-extra_specs/%s' % (flavor_id, key)), json.dumps(kwargs))
    body = json.loads(body)
    self.validate_response(schema_extra_specs.set_get_flavor_extra_specs_key, resp, body)
    return rest_client.ResponseBody(resp, body)
