func (args Args) Get(key string) (value string, ok bool) {
	if args == nil {
		return "", false
	}
	vals, ok := args[key]
	if !ok || len(vals) == 0 {
		return "", false
	}
	return vals[0], true
}
Get the first value associated with the given key. If there are any values
associated with the key, the value return has the value and ok is set to
true. If there are no values for the given key, value is "" and ok is false.
If you need access to multiple values, use the map directly.
package main
import (
	"bytes"
	"fmt"
	"net"
	"os"
	"sort"
	"strings"
)
func isIPv6(str string) bool {
	ip := net.ParseIP(str)
	return ip != nil && strings.Contains(str, ":")
}
type Args map[string][]string