diff --git a/pin/pin.go b/pin/pin.go
index 5cbcda8..0479faa 100644
--- a/pin/pin.go
+++ b/pin/pin.go
@@ -4,16 +4,14 @@ import (
 	"fmt"
 	//"strconv"
 	//"log"
-	"surdeus.su/core/cli/mtool"
+	"io"
 	"os"
+
+	"surdeus.su/core/cli/mtool"
 )
 
 var (
-	Lflag bool
-	lval int
 	delim rune = '\n'
-	nVal int
-	chrs []rune
 	Tool = mtool.T("pin").Func(Run).Desc(
 		"print all the possible PIN combinations made of custom characters",
 	).Usage(
@@ -22,39 +20,46 @@ var (
 )
 
 func Pow(x, p int) int {
-	ret := 1 
+	ret := 1
 	for i:=0 ; i<p ; i++ {
 		ret *= x
 	}
 	return ret
 }
 
-func GetPin(s []rune, l int, i int) string {
+func GetPin(chars []rune, length int, i int) string {
 	ret := ""
-	slen := len(s)
-	for j:=0 ; j<l ; j++ {
-		ret = string(s[ ( i/Pow(slen, j) ) % slen] ) + ret
+	slen := len(chars)
+	for j:=0 ; j<length ; j++ {
+		ret = string(chars[ ( i/Pow(slen, j) ) % slen] ) + ret
 	}
 	return ret
 }
 
-func printPins(s []rune, l int) {
-	n := Pow(len(s), l)
+func FprintPins(
+	output io.Writer,
+	chars []rune,
+	length int,
+) {
+	n := Pow(len(chars), length)
 	for i:=0 ; i<n ; i++ {
-		pin := GetPin(s, l, i)
-		if Fits([]rune(pin)) {
-			fmt.Println(GetPin(s, l, i))
+		pin := GetPin(chars, length, i)
+		if Fits([]rune(pin), chars, length) {
+			fmt.Fprintln(
+				output,
+				GetPin(chars, length, i),
+			)
 		}
 	}
 }
 
-func Fits(s []rune) bool {
+func Fits(s []rune, chrs []rune, maxReps int) bool {
 	a := make([]int, len(chrs))
 	for i, v1 := range chrs {
 		for _, v2 := range s {
 			if v1 == v2 {
 				a[i]++
-				if a[i] > nVal {
+				if a[i] > maxReps {
 					return false
 				}
 			}
@@ -63,38 +68,55 @@ func Fits(s []rune) bool {
 	return true
 }
 
-func Run(flags *mtool.Flags) {
+func Run(
+	flags *mtool.Flags,
+) {
+	CustomRun(
+		os.Stdin,
+		os.Stdout,
+		flags,
+	)
+}
+
+func CustomRun(
+	input io.Reader,
+	output io.Writer,
+	flags *mtool.Flags,
+) {
 	var (
 		length int
 		rFlag bool
+		mFlag bool
+		minLength int
+		maxReps int
 	)
 	var (
-		chrsString string 
+		charsString string
 		chrs []rune
 	)
 
 	flags.StringVar(
-		&chrsString,
+		&charsString,
 		"c",
 		"0123456789",
 		"character set for substitution",
 		"COMBO_CHARS",
 	)
 	flags.IntVar(
-		&lval, "min", 1,
+		&minLength, "min-len", 1,
 		"min length of the output pins",
 	)
 	flags.BoolVar(
-		&Lflag, "m", false,
-		"set the '-min' flag value to 1 (overrides the '-min' it)",
+		&mFlag, "m", false,
+		"set the '-min-len' flag value to 1 (overrides the '-min' it)",
 	)
 	flags.IntVar(
 		&length, "max", 0,
 		"max length of the output pins",
 	)
 
-	flags.IntVar(&nVal, "rep", 1, "max repeats of the rune." )
-	flags.BoolVar(&rFlag, "R", false, "make the maximum repeat equal to the length of input chars" )
+	flags.IntVar(&maxReps, "max-reps", 1, "max repeats of the rune." )
+	flags.BoolVar(&rFlag, "r", false, "make the -max-reps value equal to the length of input chars" )
 
 	_ = flags.Parse()
 
@@ -103,30 +125,30 @@ func Run(flags *mtool.Flags) {
 		os.Exit(1)
 	}*/
 
-	chrs = []rune(chrsString)
+	chrs = []rune(charsString)
 
 	if length == 0 {
 		length = 4
 	}
 
-	if Lflag {
-		lval = 1
+	if mFlag {
+		minLength = 1
 	}
 
 	if rFlag {
-		nVal = len(chrs)
+		maxReps = len(chrs)
 	}
 
-	if lval != 0 {
-		if lval > length {
+	if minLength != 0 {
+		if minLength > length {
 			flags.Usage()
 			os.Exit(1)
 		}
-		for i := lval ; i<=length ; i++ {
-			printPins(chrs, i)
+		for i := minLength ; i<=length ; i++ {
+			FprintPins(output, chrs, i)
 		}
 	} else {
-		printPins(chrs, length)
+		FprintPins(output, chrs, length)
 	}
 
 }