Wrote example for ReplaceAll(); fixed out-of-bounds bug in Expand()

regex/example_test.go

@@ -154,3 +154,11 @@ func ExampleReg_Longest() {
 	// Output: x
 	// xx
 }
+
+func ExampleReg_ReplaceAll() {
+	regexStr := `(\d)(\w)`
+	inputStr := "5d9t"
+	regexComp := regex.MustCompile(regexStr)
+	fmt.Println(regexComp.ReplaceAll(inputStr, `$2$1`))
+	// Output: d5t9
+}