code: function validateModel(json, model) {
      var schemaKeys = [];
      for (var keyInSchema in model) {
        schemaKeys.push(keyInSchema);
      }
      // Check if foreing keys are allowed.
      if (!model[SCHEMAALLOWUNKNOWN]) {
        // TODO ensure that null and false enter here.
        checkUnknown(json, schemaKeys);
      }
      for (var schemaKeyI = 0; schemaKeyI < schemaKeys.length; schemaKeyI++) {
        var node = null;
        var schemaKey = schemaKeys[schemaKeyI];
        if (json[schemaKey]) {
          node = json[schemaKey];
        }
        if (!isReservedWord(schemaKey)) {
          validateNode(node, model[schemaKey], schemaKey);
        }
      }
    }
docs: Validate model. Mode is an object in the schema, it can be root node or an object inside it.
  @param  {[type]} json  [description]
  @param  {[type]} model [description]
  @return {[type]}       [description]