code: def trace(fout=None, format=None, byteorder=sys.byteorder, nanosecond=False):
      
      str_check(fout or '', format or '')
      return TraceFlow(fout=fout, format=format, byteorder=byteorder, nanosecond=nanosecond)
docs: Trace TCP flows.
  
      Keyword arguments:
          * fout -- str, output path
          * format -- str, output format
          * byteorder -- str, output file byte order
          * nanosecond -- bool, output nanosecond-resolution file flag