code: func canonicalize(rawurls ...string) []string {
  	var canonicalized []string
  	for _, rawurl := range rawurls {
  		u, err := url.Parse(rawurl)
  		if err == nil {
  			if u.Scheme == "http" || u.Scheme == "https" {
  				// Trim trailing slashes
  				for len(u.Path) > 0 && u.Path[len(u.Path)-1] == '/' {
  					u.Path = u.Path[0 : len(u.Path)-1]
  				}
  				u.Fragment = ""
  				u.RawQuery = ""
  				canonicalized = append(canonicalized, u.String())
  			}
  		}
  	}
  	return canonicalized
  }
docs: // canonicalize takes a list of URLs and returns its canonicalized form, i.e.
  // remove anything but scheme, userinfo, host, path, and port.
  // It also removes all trailing slashes. Invalid URLs or URLs that do not
  // use protocol http or https are skipped.
  //
  // Example:
  // http://127.0.0.1:9200/?query=1 -> http://127.0.0.1:9200
  // http://127.0.0.1:9200/db1/ -> http://127.0.0.1:9200/db1