code: function (values) {
        // first assume ret is already object with 'known':
        var ret = values;
        // if it's an array, replace with object that has 'known':
        if (_.isArray(values)) { ret = { known: values }; }
        // Make sure it has a type:
        if (!ret.type) { ret.type = 'string' };
        // Add enum if running in strict mode:
        if (config.get('strict')) {
          ret.enum = ret.known;
        }
        return ret;
      }
docs: enumSchema checks the global config for strictness.  If not strict, returns a schema that matches a string.  If strict, returns a schema that matches a string which can only be the known set of values.  Also includes a custom key called 'known' which records the original set of known values regardless of the config setting.  The parameter to enumSchema can be either an array, or an object which at least contains a 'known' key.