code: func NewValuesFunc(offset int, retTp *types.FieldType, ctx context.Context) *ScalarFunction {
  	bt := &builtinValuesSig{newBaseBuiltinFunc(nil, ctx), offset}
  	return &ScalarFunction{
  		FuncName: model.NewCIStr(ast.Values),
  		RetType:  retTp,
  		Function: bt,
  	}
  }
docs: // NewValuesFunc creates a new values function.