code: func DetectChannelType(channelID string) ChannelType {
  	// intentionally ignore the error and just default to CTypeUnknown
  	switch r, _ := utf8.DecodeRuneInString(channelID); r {
  	case 'C':
  		return CTypeChannel
  	case 'G':
  		return CTypeGroup
  	case 'D':
  		return CTypeDM
  	default:
  		return CTypeUnknown
  	}
  }
docs: // DetectChannelType converts a channelID to a ChannelType.
  // channelID must not be empty. However, if it is empty, the channel type will default to Unknown.