package util import (	"fmt"	"html/template"	"log"	"net/url"	"strings" 	"github.com/gomarkdown/markdown"	"github.com/microcosm-cc/bluemonday"	// "errors") /* util.Eout example invocationsif err != nil {  return util.Eout(err, "reading data")}if err = util.Eout(err, "reading data"); err != nil {  return nil, err}*/ type ErrorDescriber struct {	environ string // the basic context that is potentially generating errors (like a GetThread function, the environ would be "get thread")} // parametrize Eout/Check such that error messages contain a defined context/environfunc Describe(environ string) ErrorDescriber {	return ErrorDescriber{environ}} func (ed ErrorDescriber) Eout(err error, msg string, args ...interface{}) error {	msg = fmt.Sprintf("%s: %s", ed.environ, msg)	return Eout(err, msg, args...)} func (ed ErrorDescriber) Check(err error, msg string, args ...interface{}) {	msg = fmt.Sprintf("%s: %s", ed.environ, msg)	Check(err, msg, args...)} // format all errors consistently, and provide context for the error using the string `msg`func Eout(err error, msg string, args ...interface{}) error {	if err != nil {		// received an invocation of e.g. format:		// Eout(err, "reading data for %s and %s", "database item", "weird user")		if len(args) > 0 {			return fmt.Errorf("%s (%w)", fmt.Sprintf(msg, args...), err)		}		return fmt.Errorf("%s (%w)", msg, err)	}	return nil} func Check(err error, msg string, args ...interface{}) {	if len(args) > 0 {		err = Eout(err, msg, args...)	} else {		err = Eout(err, msg)	}	if err != nil {		log.Fatalln(err)	}} func Contains(slice []string, s string) bool {	for _, item := range slice {		if item == s {			return true		}	}	return false} var contentGuardian = bluemonday.UGCPolicy()var strictContentGuardian = bluemonday.StrictPolicy() // Turns Markdown input into HTMLfunc Markup(md template.HTML) template.HTML {	mdBytes := []byte(string(md))	// fix newlines	mdBytes = markdown.NormalizeNewlines(mdBytes)	maybeUnsafeHTML := markdown.ToHTML(mdBytes, nil, nil)	// guard against malicious code being embedded	html := contentGuardian.SanitizeBytes(maybeUnsafeHTML)	return template.HTML(html)} func SanitizeStringStrict(s string) string {	return strictContentGuardian.Sanitize(s)} // make a string be suitable for use as part of a urlfunc SanitizeURL(input string) string {	input = strings.ReplaceAll(input, " ", "-")	input = url.PathEscape(input)	// TODO(2022-01-08): evaluate use of strict content guardian?	return strings.ToLower(input)}