code: func Bool(value string, def bool) bool {
  	if len(value) == 0 {
  		return def
  	}
  
  	switch strings.ToLower(value) {
  	case "true", "1", "on", "yes", "t":
  		return true
  	case "false", "0", "off", "no", "f":
  		return false
  	default:
  		return false
  	}
  }
docs: // Bool returns the boolean state associated with the given value, or the
  // value "def", if the value is blank.
  //
  // The "boolean state associated with a given key" is defined as the
  // case-insensitive string comparison with the following:
  //
  // 1) true if...
  //   "true", "1", "on", "yes", or "t"
  // 2) false if...
  //   "false", "0", "off", "no", "f", or otherwise.