code: func (a *Args) GetBool(key string) bool {
  	switch b2s(a.Peek(key)) {
  	// Support the same true cases as strconv.ParseBool
  	// See: https://github.com/golang/go/blob/4e1b11e2c9bdb0ddea1141eed487be1a626ff5be/src/strconv/atob.go#L12
  	// and Y and Yes versions.
  	case "1", "t", "T", "true", "TRUE", "True", "y", "yes", "Y", "YES", "Yes":
  		return true
  	default:
  		return false
  	}
  }
docs: // GetBool returns boolean value for the given key.
  //
  // true is returned for "1", "t", "T", "true", "TRUE", "True", "y", "yes", "Y", "YES", "Yes",
  // otherwise false is returned.