In schema, I don't see a way to define allowed values per field. Here is an example with `allowed_values` attribute ``` { "type": "object", "$schema": "http://json-schema.org/draft-04/schema#", "properties": { "city": { "type": "string", allowed_values: ["Paris", "London"] }, "country": { "type": "string" } }, "required": ["country"] } ``` It means it returns an error if I pass a different city. Is there any workaround to do this?