Bracket evaluation, Bracket Validator - golang

// Parentheses pairing ({}[]()<>)
// 
package main;

import (
	"fmt"
	"strings"
)
func main() {
	fmt.Println(stringMatch("{[(])}"));
}

func stringMatch(input string) bool {
	var pushChars, popChars string =  "{[(<" ,"}])>";
	var stack []rune
	var pop rune;
	for _, r := range input {
		if strings.ContainsRune(pushChars, r) {
			stack = append(stack, r);
		} else  if strings.ContainsRune(popChars, r) {
			if (len(stack) > 0) {
				pop = stack[len(stack)-1:len(stack)][0];
				k := pushChars[strings.IndexRune(popChars, r)]
				fmt.Println(k, pop, r)
				if (rune(k) == pop) {
					stack = stack[: len(stack)-1]
				} else {
					return false;
				}
			} else {
				return false;
			}
		}
	}
	return len(stack) == 0; 
}