func IsURL(str string) bool {
	return checkURL(str, "url")
}
IsURL returns true if the provided str is an HTTP(S) URL.
package urlutil
import (
	"regexp"
	"strings"
)
var (
	validPrefixes = map[string][]string{
		"url":       {"http://", "https://"},
		"git":       {"git://", "github.com/", "git@"},
		"transport": {"tcp://", "udp://", "unix://"},
	}
	urlPathWithFragmentSuffix = regexp.MustCompile(".git(?:#.+)?$")
)