Improved code quality

src/asm/Number.go

@@ -1,7 +1,7 @@
 package asm
 
 import (
-	"fmt"
+	"strconv"
 )
 
 // Number operates with just a number.
@@ -11,7 +11,7 @@ type Number struct {
 
 // String returns a human readable version.
 func (data *Number) String() string {
-	return fmt.Sprintf("%d", data.Number)
+	return strconv.Itoa(data.Number)
 }
 
 // Number adds an instruction with a number.