code: func (d *dataEncoder) charCountBits(dataMode dataMode) int {
  	switch dataMode {
  	case dataModeNumeric:
  		return d.numNumericCharCountBits
  	case dataModeAlphanumeric:
  		return d.numAlphanumericCharCountBits
  	case dataModeByte:
  		return d.numByteCharCountBits
  	default:
  		log.Panic("Unknown data mode")
  	}
  
  	return 0
  }
docs: // charCountBits returns the number of bits used to encode the length of a data
  // segment of type dataMode.