new operator 'groupby'

term.go

@@ -235,6 +235,10 @@ func (t *term) errDivisionByZero() error {
 	return t.tk.Errorf("division by zero")
 }
 
+func (t *term) errKeyNotFound(key any) error {
+	return t.tk.Errorf("key '%v' not found", key)
+}
+
 func (t *term) Errorf(template string, args ...any) (err error) {
 	err = t.tk.Errorf(template, args...)
 	return