code: func contentEncoding(ce string, charsets ...string) bool {
  	_, ce = split(strings.ToLower(ce), ";")
  	_, ce = split(ce, "charset=")
  	ce, _ = split(ce, ";")
  	for _, c := range charsets {
  		if ce == c {
  			return true
  		}
  	}
  
  	return false
  }
docs: // Check the content encoding against a list of acceptable values.