moved a subset of source file to the kern package

t_scanner_test.go

@@ -9,6 +9,8 @@ import (
 	"reflect"
 	"strings"
 	"testing"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 func TestScanner(t *testing.T) {
@@ -60,7 +62,7 @@ func TestScanner(t *testing.T) {
 		/* 38 */ {`\`, SymError, errors.New("incomplete escape sequence"), nil},
 		/* 39 */ {`"string"`, SymString, "string", nil},
 		/* 40 */ {`identifier`, SymIdentifier, "identifier", nil},
-		/* 41 */ {`1.2(3)`, SymFraction, newFraction(37, 30), nil},
+		/* 41 */ {`1.2(3)`, SymFraction, kern.NewFraction(37, 30), nil},
 	}
 
 	for i, input := range inputs {