a way to check file extensions

extensions.go

package main

import (
	"fmt"
	"strings"
)

func main() {

	ext := ".WEBM"

	ext_check := IsValidExt(ext)
	if !ext_check {
		fmt.Println("no way")
	} else {
		fmt.Println("cool bro")
	}

}

func IsValidExt(ext string) bool {

	validExt := map[string]bool{
		".jpg":  true,
		".jpeg": true,
		".png":  true,
		".gif":  true,
		".webm": true,
	}

	if validExt[strings.ToLower(ext)] {
		return true
	}

	return false

}