code: def _normalized_serial(self):
          
          if self._serial is None:
              return None
          normalized_serial = self._serial.replace(' ', '_')
          normalized_serial = normalized_serial.replace(':', '-')
          return normalized_serial
docs: Normalized serial name for usage in log filename.
  
          Some Android emulators use ip:port as their serial names, while on 
          Windows `:` is not valid in filename, it should be sanitized first.